Oracle

Oracle

Oracle Database is a Multi-Model Database Management System created by Oracle Corporation.
Sean Robertson

Sean Robertson

1671431136

PL/SQL Interview Questions and Answer

This tutorial shows 200+ most important and common SQL and PL/SQL Questions and answer. Learn how to answer the PL/SQL, SQL interview question.

65+ Theory and  10+ Video interview question and answer for PL/SQL. This all questions are enough for any interview. So come and read theory with Practicals.

I have put all my knowledge and experience to make 200+ most important and common  SQL and PL/SQL Questions and answer for you only 

I want to help each one of you to succeed in the PL/SQL Job Interview. If you want after interview question and answer we can conduct one short round of interview.

And my friends at the end of this course, you will know all the way  to answer the most common SQL interview questions.

So are you ready to prepare the most common question and  answers of PL/SQL.

Some of PL/SQL Question

   1.  What is Package

   2. How to write  Package specification

   3. What is Package body

   4. What is Procedure

   5. How to execute procedure from Pl/SQL block

   6. How to drop or delete procedure 

   7. What is Function

   8. how to call function in PL/SQL block

   9. How to call procedure in begin block

   10. How to call package

   11. What is substr Function?

   12. What is ceil Function?

   13. What is translate Function?

   14. select translate('12Benchpe34','1234','5678') from dual;

   15. select translate('1234Benchpe567','1234567','www..in') from dual;

What you’ll learn

  •        Fresher and Experienced they will refresh their PL/SQL knowledge. and they can pass any interview in any company with this all video interview question and answer

Are there any course requirements or prerequisites?

  •        Basic knowledge in PL/SQL or SQL before starting this course.
  •        SQL Developer tools or oracle PL/SQL Tools
  •        Pen and Notebook always, to understand more and more

Who this course is for:

  •        Any one who has basic knowledge in PL/SQL or SQL.
  •        Any one who want to Learn database
  •        Fresher and Experienced

#sql #database #oracle #interviewquestions 

PL/SQL Interview Questions and Answer
Sheldon  Grant

Sheldon Grant

1670296757

7 Great ERD Tools for Oracle Database Modeling

Want to start your next Oracle database project? Find out the best Oracle ER diagram tool and save yourself some time and extra work!

Oracle is one of the best and most popular database management systems (DBMSs) in the world. Many database architects prefer to use Oracle because of its easy networking and interaction, cross-platform service, simple administration and maintenance, and other benefits. On the other hand, an ER DIAGRAM (entity-relationship diagram) is an essential tool for DATA MODELING. So it's worth finding the best ERD tool for Oracle to use on your next project.

In this article, we’ll explore some of the most popular data modeling tools for the Oracle database.

7 Great ERD Tools for Oracle Database Modeling

1. Vertabelo

VERTABELO is a modern online ERD tool that supports data modeling for Oracle and many other databases (including MySQL, SQL Server, PostgreSQL, etc.). It provides a clean, modern, and responsive user interface (UI) and supports popular NOTATIONS like Crow's Foot, IDEF1X, and UML to draw your LOGICAL AND PHYSICAL MODELS.

ERD tool for oracle

This data modeler comes with many modern features, such as SQL generation, reverse engineering, and model validation. You can create or remove all selected elements from your ER diagram in your physical database with the SQL GENERATION feature. Also, you can import an existing database to the Vertabelo ERD tool using the reverse engineering feature and modify it using the online data modeling features. Finally, Vertabelo validates your logical and physical ER data models against the selected database management system (DBMS). You can read more on VERTABELO MODEL VALIDATION HERE.

As an online ERD tool for Oracle, Vertabelo allows you to SHARE YOUR MODELS with others, including customers or partners who do not have Vertabelo accounts. Learn more about HOW VERTABELO SUPPORTS COLLABORATION HERE.

2. Visual Paradigm

ERD tool for oracle

VISUAL PARADIGM is an online multi-diagramming tool that provides different notations to draw various diagrams, including ER diagrams. Visual Paradigm supports many popular DBMSs like Oracle, MySQL, SQL Server, and Sybase.

This ERD tool for Oracle supports drawing conceptual, logical, and physical data models. It provides a clean and modern user interface with the required notations, including Crow's Foot.

The 'Table Record Editor' is a unique feature that lets you enter sample records into the entities and understand the data formats inserted into the database. This ERD tool's 'Model Transitor' feature saves time by deriving logical and physical models from their upper levels, without the need to create them from scratch.

You can use this ERD tool to create DDL files from the selected entities or the entire model; this will automatically create the physical database elements for an Oracle database. Also, you can patch revisions made in the data model into the physical database with this tool. You can use the reverse engineering feature to import an existing database to it and edit it visually.

 3. Navicat

NAVICAT comes as an offline ERD tool for Oracle. It supports many other DBMSs, such as MySQL, SQL Server, and MariaDB. This tool is available in Windows, macOS, and Linux versions.

ERD tool for oracle

This ERD tool comes with Crow's Foot, IDEF1X, and UML notations. Its user-friendly interface allows you to draw all data models, from conceptual to physical. Also, the tool provides automated features to create logical and physical models from their upper levels, which saves time.

Navicat’s reverse engineering feature lets you import and modify physical databases, while its 'Export SQL' feature generates SQL scripts from each component of the physical data model.

4. SqlDBM

ERD tool for oracle

SQLDBM is an online ERD tool for Oracle (and SQL Server, MySQL, Amazon Redshift, etc.) that supports collaborative work among distributed teams. Users can log in from anywhere and on any platform. Also, this tool supports many other popular databases. As with other ER diagram solutions, you can model conceptual to physical data models using notations like Crow's Foot and IDEF1X.

This modeler allows you to automatically create DDL files from your physical data model. The reverse engineering feature lets you copy–paste or upload SQL DDL scripts generated from a physical database to create a data model. It also facilitates version control.

5. Astah Professional

ERD tool for oracle

ASTAH PROFESSIONAL is an offline multi-diagramming tool. It allows you to create ER diagrams as well as UML and data flow diagrams and many others. It’s available in macOS, Windows, Ubuntu, and CentOS versions.

As an ERD tool for Oracle, Astah Professional provides Crow's Foot and IDEF1X notations. You can export the components of your data model to SQL (SQL-92) with the 'Export Excel' feature. There’s also a reverse engineering feature so you can import an existing database into the tool.

Astah Professional is an offline program suitable for individual work. It does not directly support remote collaboration like an online tool would.

6. Lucidchart

LUCIDCHART is another multi-diagramming online tool that facilitates drawing ER diagrams. It supports Oracle and many other databases as well as Salesforce.

ERD tool for oracle

You can draw your ER diagram in Lucidchart manually or generate it automatically by importing data. If you draw it manually, the tool has templates and a shapes library to make things faster.

With this ERD tool, you can generate SQL scripts to export your data model to Oracle and other supported DBMSs. Lucidchart also provides you with many options to share your models with others.

7. ERDPlus

ERD tool for oracle

ERDPLUS is another ERD tool for Oracle. It’s an online solution with all the required features and notations to draw your conceptual to physical ER diagrams. In addition to Oracle, ERDPlus supports MySQL, IBM DB2, SQL Server, Postgres, and many other popular databases. Also, there’s an automated feature to create a physical model from a logical ER diagram.

ERDPlus creates SQL scripts to automate building your Oracle database from a physical model. In addition, this online ERD tool lets you export your diagrams in many different formats.

This tool is suitable for modeling your data from scratch, but it does not support reverse engineering.

What's the Best ERD Tool for Oracle?

Many online and offline ERD tools are available to model your data for Oracle databases. When choosing the best, you must consider many factors. Let’s briefly summarize WHAT TO LOOK FOR IN YOUR ER DIAGRAM TOOL before we close this article.

In the modern database industry, it's vital to have efficient data modeling. Any good tool should save time and cost while supporting collaborative work, easy data modeling via a clean and contemporary UI, a comprehensive range of supported DBMSs, etc. For these reasons, online ERD tools that offer model sharing and collaborative features (like Vertabelo, SqlDBM, etc.) are at the top of my list. I’d also add that automated features like DDL generation and reverse engineering save a lot of time and bother.

So, when you look for a data modeling tool for your next Oracle database project, keep these things in mind.

Original article source at: https://www.vertabelo.com/

#oracle #tool 

7 Great ERD Tools for Oracle Database Modeling
Joseph  Norton

Joseph Norton

1668918771

Oracle SQL Tutorial for Beginners

In this tutorial, you'll learn about Oracle SQL and how to use Oracle SQL. Learn how to install Oracle, SQL Developer and gain a sound understanding of SQL, SQL PLus and SQL Developer

Oracle SQL. 

You will learn how to use the industry standard tool for working with a Relational Database. You will also learn many other things, from  constructing simple queries to creating your own  tables.

Oracle SQL*Plus. 

  •    After the course you should have a  good understanding of SQL*Plus, from starting it, to  creating simple reports on it.

Oracle SQL Developer.

  •    We will go over the SQL Developer components and see how it hangs together

What you’ll learn

  •        Learn how to install Oracle, SQL Developer and gain a sound understanding of SQL, SQL PLus and SQL Developer

Are there any course requirements or prerequisites?

  •        Basic PC knowledge

Who this course is for:

  •        Beginner Oracle SQL

#oracle #sql #database 

Oracle SQL Tutorial for Beginners
Daisy Rees

Daisy Rees

1668584957

Home Lab with Oracle Cloud and Ansible

Learn how to provision a home lab with Oracle Cloud and Ansible. How you can do a full infrastructure provisioning of a pair of web servers on a Cloud provider, with SSL certificates and monitoring metrics with Prometheus.

Imagine for a moment that you been working hard to setup a website, protected with SSL, and then your hardware fails. This means that unless you have a perfect backup of your machine, you will need to install all the software and configuration files by hand.

What if it's not just one server but many? The amount of time you will need to fix all of them will grow exponentially – and because is a manual process it will be more error-prone.

And then the nightmare scenario: You don't have an up-to-date backup, or you have incomplete backups. Or the worst – there are no backups at all. This last case is more common than you think, especially in home labs where you are tinkering and playing around with stuff by yourself.

In this tutorial, I'll show you how you can do a full infrastructure provisioning of a pair of web servers on a Cloud provider, with SSL certificates and monitoring metrics with Prometheus.

What You Need for This Setup

The first thing you need is a cloud provider. Oracle Cloud offers a Free Tier version of their cloud services, which allows you to setup virtual machines for free. This is great for a home lab with lots of rich features that you can use to try new tools and techniques.

You'll also need an automation tool. I used Ansible because its doesn't have many requirements (you only need an SSH daemon and public key authentication to get things going). I also like it because it works equally well regardless of the cloud environment you are trying to provision.

In this tutorial we will use the Open Source version of this tool, as it is more than sufficient for our purposes.

What's included in the Ansible playbook

An Ansible playbook is nothing more than a set of instructions you define to execute tasks that will change the status of a host. These actions are carried out on an inventory of hosts you define.

Here, you are going to learn about the following:

  • How to clean inventory sources by using the proper layout in your playbooks.
  • How to provision two NGINX instances, with the request of their proper free SSL certificates using Certbot.
  • How to set up the local Linux firewalls and add a Prometheus node_exporter agent and one scraper to collect that data.
  • Concepts like variables, roles (with task inclusion), and conditional execution.
  • Important techniques like task tagging, debug messages, and static validation with ansible-lint.

All the code can be found in this GitHub repository.

What You Should Know Before Trying This

Because we will cover several tasks here, you will probably need to be familiar with several things (I'll provide links as we go along):

What is not included here

OCI Cloud has a complete REST API to manage a lot of aspects of their cloud environment. Their setup page (specifically the SDK) is also very detailed.

You'll Probably Do Things Differently in Production.

Installing the OCI-Metrics-datasource instead of Prometheus agents on a virtual machine

You can go to this page to install it on your Grafana instance (Bare metal or Cloud). Also you need to setup your credentials and permissions as explained here.

This is probably the most efficient way to monitor your resources as you do not need to run agents on your virtual machines. But I will install instead a Prometheus node_exporter agent and scraper that will be visible from a Grafana Cloud instance.

An exposed Prometheus on the Internet endpoint is not a good idea

It is very clear, I'm exposing my Prometheus scraper to the Internet so Grafana cloud can reach it. On an Intranet with a private cloud and your local Grafana, this is not an issue – but here, a Prometheus agent pushing data to Grafana would be a better option.

Still, Grafana provides a list of public IP addresses that you can use to setup your allow list.

So the following will work:

oracle_cloud_ingress_rules

Oracle Cloud Ingress Rules

But it is not the best. Instead, you want to restrict the specific IP addresses that can pull data from your exposed services. The prometheus exporter can be completely hidden from Grafana on port 9100. Instead we only need to expose the Prometheus scraper that listens on port 9000.

For this home lab, it is not a big deal having such services fully exposed. But if you have a server with sensitive data, you must restrict who can reach the service!

An alternative to the Prometheus endpoint is to push the data to Grafana by using a Grafana agent but I will not cover that option here.

Playbook Analysis

Ansible lets you have a single file with the playbook instructions, but eventually you will find that such a structure is difficult to maintain.

For my playbook I decided to keep the suggested structure:

tree -A 
.
├── inventory
│   └── cloud.yaml
├── oracle.yaml
├── roles
│   └── oracle
│       ├── files
│       │   ├── logrotate_prometheus-node-exporter
│       │   ├── prometheus-node-exporter
│       │   └── requirements_certboot.txt
│       ├── handlers
│       │   └── main.yaml
│       ├── meta
│       ├── tasks
│       │   ├── controller.yaml
│       │   ├── main.yaml
│       │   ├── metrics.yaml
│       │   └── nginx.yaml
│       ├── templates
│       │   ├── prometheus-node-exporter.service
│       │   ├── prometheus.service
│       │   └── prometheus.yaml
│       └── vars
│           └── main.yaml
└── site.yaml

Below is a brief description of how the content is organized:

  1. You can have more than one site. You control that inside the site.yaml file.
  2. The host list is inside the inventory directory. You can have more than one inventory file or scripts to generate the hostlist, or a combination of both.
  3. The roles/oracle group the tasks. We only have one role called 'oracle' because that's the cloud provider I'm focusing on here.
  4. Our playbook uses metadata in the form of variables, with each one defined on the 'vars' directory. That way we can customize the behaviour of the playbook in multiple places:
---
# Common variables for my Oracle Cloud environments
controller_host: XXXX.com
ssl_maintainer_email: YYYYYY@ZZZZ.com
architecture: arm64
prometheus_version: 2.38.0
prometheus_port: 9090
prometheus_node_exporter_nodes: "['X-server1:{{ node_exporter_port }}', 'Y-server2:{{ node_exporter_port }}' ]"
node_exporter_version: 1.4.0
node_exporter_port: 9100
internal_network: QQ.0.0.0/24

The roles/oracle files directory contains files that can be copied as is to the remote directory. The templates' directory is similar, but the files in there can be customized for each host by using the Jinja templating language.

# A template for the prometheus scraper configuration file
---
global:
    scrape_interval: 30s
    evaluation_interval: 30s
    scrape_timeout: 10s
    external_labels:
        monitor: 'oracle-cloud-metrics'

scrape_configs:
  - job_name: 'node-exporter'
    static_configs:
      - targets: {{ prometheus_node_exporter_nodes }}
    tls_config:
      insecure_skip_verify: true

The 'tasks' directory is where we store our tasks, that is the actions that will modify the server state. Note that Ansible will not execute tasks if it's not necessary. The idea is that you can re-run a playbook as many times as needed and the final state will be the same.

# Fragment of the nginx tasks file. See how we notify a handler to restart nginx after the SSL certificate is renewed.
---
- name: Copy requirements file
  ansible.builtin.copy:
    src: requirements_certboot.txt
    dest: /opt/requirements_certboot.txt
  tags: certbot_requirements

- name: Setup Certbot
  pip:
    requirements: /opt/requirements_certboot.txt
    virtualenv: /opt/certbot/
    virtualenv_site_packages: true
    virtualenv_command: /usr/bin/python3 -m venv
  tags: certbot_env

- name: Get SSL certificate
  command:
    argv:
      - /opt/certbot/bin/certbot
      - --nginx
      - --agree-tos
      - -m {{ ssl_maintainer_email }}
      - -d {{ inventory_hostname }}
      - --non-interactive
  notify:
    - Restart Nginx
  tags: certbot_install

There is one special directory called 'handlers'. There we define actions that must happen if a task changes the state of our host.

We now have a picture of how all the pieces work together, so let's talk about some specific details.

Firewall provisioning

With Ansible, you can replace a sequence of commands like this:

sudo firewall-cmd --permanent --zone=public --add-service=http
sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload

With a firewalld module:

---
- name: Enable HTTP at the Linux firewall
  firewalld:
    zone: public
    service: http
    permanent: true
    state: enabled
    immediate: yes
  notify:
    - Reload firewall
  tags: firewalld_https

- name: Enable HTTPS at the Linux firewall
  firewalld:
    zone: public
    service: https
    permanent: true
    state: enabled
    immediate: yes
  notify:
    - Reload firewall
  tags: firewalld_https

Common tasks have nice replacements

So instead of running SUDO with a privileged command:

sudo dnf install -y nginx
sudo systemctl enable nginx.service --now

You can have something like this:

# oracle.yaml file, which tells which roles to call, included from site.yaml
---
- hosts: oracle
  serial: 2
  remote_user: opc
  become: true
  become_user: root
  roles:
  - oracle
# NGINX task (roles/oracle/tasks/nginx.yaml)
- name: Ensure nginx is at the latest version
  dnf:
    name: nginx >= 1.14.1
    state: present
    update_cache: true
  tags: install_nginx
# And a handler that will restart NGINX after it gets modified (handlers/main.yaml)
---
- name: Restart Nginx
  service:
    name: nginx
    state: restarted
- name: Reload firewall
  command: firewall-cmd --reload

How to Run the Playbooks

Normally you don't wait to have the whole playbook written, but you run the pieces you need in the proper order. At some point you will have your whole playbook finished and ready to go.

Make sure the playbook behaves properly with --check before making any changes

The very first step is to check your playbook file for errors. For that you can use yamllint:

yamllint roles/oracle/tasks/main.yaml

But doing this for every yaml file in your playbook can be tedious an error-prone. As an alternative, you can run the playbook in a 'dry-run' mode, to see what will happen without actually making any changes:

asciicast

Another way to gradually test a complex playbook is by executing a specific task by using a tag or group of tags. That way you can do controlled execution of your playbook:

Keep in mind that this will not execute any dependencies that you may have defined on you playbook, tough:

asciicast

Constrain where the playbook runs with --limit and --tags

Say that you are only interested in running your playbook on a certain host. In that case, you can also do that by using the --limit flag:

ansible-playbook --inventory inventory --limit fido.yourcompany.com --tags certbot_renew site.yaml

asciicast

Here we did run only a task tagged certbot_renew on the host fido.yourcompany.com.

How to deal with a real issue

Let's make this interesting: say that I was eager to update one of my requirements for certboot, and I changed versions if pip to '22.3.1':

pip==22.3.1
wheel==0.38.4
certbot==1.32.0
certbot-nginx==1.32.0

When I run the playbook we have a failure:

asciicast

This is an issue with the versions if specified on the requirements_certboot.txt file. When you install a Python library using a virtual environment you can specify versions like this:

pip22.3.1
wheel0.38.1
certbot1.23.0
certbot-nginx1.23.0

To fix the issue, we will revert the versions used on the file and then re-run the requirements file and Certbot installation task:

- name: Setup Certbot
  pip:
    requirements: /opt/requirements_certboot.txt
    virtualenv: /opt/certbot/
    virtualenv_site_packages: true
    virtualenv_command: /usr/bin/python3 -m venv
    state: forcereinstall
  tags: certbot_env
ansible-playbook --inventory inventory --tags certbot_env site.yaml

See it in action:

asciicast

How to run the whole playbook

ansible-playbook --inventory inventory site.yaml

It is time to run the whole playbook:

asciicast

Wrapping up

This tutorial only touches the surface of what you can do with Ansible. So below are a few more resources you should explore to learn more:

Original article source at https://www.freecodecamp.org

#cloud #oracle #ansible #prometheus

Home Lab with Oracle Cloud and Ansible
Ilaria  Dugg

Ilaria Dugg

1666596360

Top Oracle Crypto Projects | Crypto Oracles Services

A blockchain oracle is any device or entity that connects a deterministic blockchain with off-chain data. These oracles enter each data entry through an external transaction.

The technology is blockchain-agnostic and is constantly working to integrate with more blockchains so that all blockchains can have access to secure and reliable off-chain data. And best of all, the documentation is great for beginner and experienced engineers alike.

In this article you will see Top 20 Oracle Crypto Projects | Crypto Oracles Services
 

1. Chainlink (LINK)

DescribeWebsiteExchange

Chainlink is a blockchain abstraction layer that enables universally connected smart contracts. Through a decentralized oracle network, Chainlink allows blockchains to securely interact with external data feeds, events and payment methods, providing the critical off-chain information needed by complex smart contracts to become the dominant form of digital agreement.

The Chainlink Network is driven by a large open-source community of data providers, node operators, smart contract developers, researchers, security auditors and more. The company focuses on ensuring that decentralized participation is guaranteed for all node operators and users looking to contribute to the network.

LinkBuy

2. Winklink (WIN)

DescribeWebsiteExchange

The first TRON ecosystem comprehensive oracle WINkLink fully integrates the real world with the blockchain space, will be able to provide reliable, unpredictable and verifiable random numbers, and fully restore trust and improve user experience by tapping into data, events, and payment systems etc. from the real world.

WIN, a TRON-based TRC20 token, will be the governance token of the WINkLink oracle network. 

LinkBuy

3. Api3 (API3)

DescribeWebsiteExchange

API3’s stated goal is to allow decentralized versions of APIs to be built, managed and monetized at scales.

Oracles are a form of middleware that sit in between APIs and smart contracts — increasing costs and centralization. API3 intends to get around this problem by enabling API providers to operate their very own nodes.

LinkBuy

4. Tellor (TRB)

DescribeWebsiteExchange

Tellor’s oracle works by incentivizing data reporters to put valid data on-chain while also disincentivizing bad reports via disputes and slashing. Becoming a reporter requires no verification process i.e. permissionless. Anyone anywhere in the world can be a reporter using open source software, a unique characteristic among blockchain oracles.

When oracle users request the value of an off-chain data point (e.g. BTC/USD), data reporters compete to add this value to an on-chain data-bank, accessible by all smart contracts on the networks Tellor supports (Ethereum, Polygon, Algorand, etc.) The frequency with which data can be updated is limited only by how much / how often users “tip” the feed with TRB.

Also unique to Tellor, data is submitted in bytes meaning the oracle is flexible and robust for nearly any blockchain application.

LinkBuy

5. Uma (UMA)

DescribeWebsiteExchange

UMA is an optimistic oracle (OO) that can record any verifiable truth onto a blockchain. The OO has been called “a human-powered truth machine” because it is flexible enough to handle ambiguity and expands the design space possible in web3.

UMA’s OO secures a diverse ecosystem of web3 applications, including cross-chain bridges, insurance protocols, prediction markets, and customizable DAO tooling products.

The Across bridge, Polymarket prediction markets, and Outcome.Finance DAO tools are all secured by UMA’s OO.

LinkBuy

6. Band protocol (BAND)

DescribeWebsiteExchange

Band Protocol is a cross-chain data oracle platform that is able to take real-world data and supply it to on-chain applications, while also connecting APIs to smart-contracts to facilitate the exchange of information between on-chain and off-chain data sources.

By supplying reputable, verifiable real-world data to blockchains, Band Protocol unlocks a range of new use cases for developers to explore — since they can now use any type of real-world data as part of their decentralized application (DApp) logic, including sports, weather, random numbers, price feed data and more.

BAND is the native token of the Band Protocol ecosystem and is used as collateral by validators involved in fulfilling data requests, as well as the main medium of exchange on BandChain — being used to paying for private data.

LinkBuy

7. Iexec rlc (RLC)

DescribeWebsiteExchange
 LinkBuy

8. Nest protocol (NEST)

DescribeWebsiteExchange

NEST Protocol is a secured decentralized oracle built on Ethereum that provides creative solutions using different modules. The NEST oracle primarily solves the problem of price on-chain through a decentralized incentive solution, the price predictor.

The NEST Oracle determined price is captured on the blockchain, with each block recording a price. The price on each block is generated by a certain algorithm. This price is called the block-price or the Nest Price, which is the verified price of the asset.

NestNodes are an important part of the NEST Protocol ecosystem. As the source of power for NEST development, it provides numerous resources and funds for the early research and development of NEST. NestNodes provide benefits and influence from the NEST ecosystem including the governance rights to the NEST protocol via initiating and exercising votes on the network.

LinkBuy

9. Dia (DIA)

DescribeWebsiteExchange

DIA (Decentralised Information Asset) is an open-source oracle platform that enables market actors to source, supply and share trustable data. DIA provides a reliable and verifiable bridge between off-chain data from various sources and on-chain smart contracts that can be used to build a variety of financial DApps.

DIA is the governance token of the platform. It is currently based on ERC-20 Ethereum protocol.

LinkBuy

10. Skey network (SKEY)

DescribeWebsiteExchange

Skey Network is the world’s first platform to successfully bridge decentralized finance (DeFi) and IoT, and will create the platform for a new economy of physical assets called the ‘Blockchain of Things’ (BoT).

The non-fungibility (i.e. uniqueness) property of Skey Network NFTs is also a game-changer when applied to IoT. Using a Skey Network NFT, every smart object in a network can have its own unique token providing proof of ownership. 

LinkBuy

11. Oraichain (ORAI)

DescribeWebsiteExchange
As an AI Layer 1 for Data Economy and Oracle services, Oraichain is the world's first intelligent and secure solutions for emerging Web3, scalable Dapps, and decentralized AI.LinkBuy

12. HAPI Protocol (HAPI)

DescribeWebsiteExchange

HAPI is the only crypto cybersecurity solution that can be integrated into DEXes and DeFi protocols preventing Money Laundering by embedding Smart Contracts and routing each transaction through it.

HAPI is a one-of-a-kind decentralized security protocol that prevents and interrupts any potential malicious activity within the blockchain space.

One can imagine HAPI being an all-encompassing, overarching protocol that combines crypto intelligence data from multiple sources allowing the most accurate information on malicious activity, and compromised wallets.

LinkBuy

13. Xyo network (XYO)

DescribeWebsiteExchange

XYO Network is a decentralized device network that anonymously collects and validates geospatial data. XYO is built on the Ethereum blockchain. Geospatial data is data that is associated with a specific location. The platform's goal is to encourage the education, research, and development of the XYO protocol in order to increase public understanding of the benefits of a geospatial location network that is driven by incentives.

XYO is an Ethereum token that powers XYO Network, a decentralized network of devices that anonymously collect and validate geospatial data.

On the XYO World platform, XYO tokens can be traded for and staked against unique ERC-721 tokens representing real-world locations.

LinkBuy

14. Xfund (XFUND)

DescribeWebsiteExchange

xFUND is the on-chain governance and access token for the Unification Oracle of Oracles and other DeFi products.

xFUND’s supply starts at 0. Its purpose is to enable off-chain governance for the entire Unification ecosystem and power a suite of products, including Oracle of Oracles. 

LinkBuy

15. Kylin network (KYL)

DescribeWebsiteExchange

Kylin Network will provide a decentralized data infrastructure solution, called DeData for Web 3.0 leveraging Polkadot and Polkadot Substrate 2.0 Off-Chain Workers including Kylin Data Oracle, Kylin Data Analytics and the Kylin Data Marketplace.

KYL is the native utility token that is used for:

Staking for data miners, validators and arbitrators. All miners are required to stake KYL with a higher stake equating in a high probability of being selected to fulfill data requests. Intermediary of Exchange. KYL will be used to pay as a transaction, query fee, and also for data access behind paywall (private APIs). On-Chain Governance. KYL Token holders are able to vote for the protocol upgrades and parameter changes on Kylin Network.

LinkBuy

16. Unmarshal (MARSH)

DescribeWebsiteExchange

Unmarshal is a Multi-chain DeFi network of indexers that provides seamless access to Blockchain data for DeFi applications. Cater data in multiple formats like APIs, Websockets, GraphQL, Notifications any many more, without the need for application developers to decode it into their native applications.

$MARSH is the utility token that powers Unmarshal’s Network and also incentivizes network contributors such as Node runners and Indexers etc.

LinkBuy

17. Umbrella network (UMB)

DescribeWebsiteExchange

Umbrella Network is a community-owned, decentralized oracle service providing secure and extensively scalable data solutions for decentralized finance (DeFi) applications. Umbrella provides access to revolutionary financial datasets for blockchain app developers in the crypto space as well as those with an interest in real-world business transactions.

The decentralization power of the Umbrella Network is centered around the UMB utility token, which is used for staking, community votes and rewards and incentives. By introducing a layer two blockchain integration, Umbrella Network creates a highly scalable oracle solution.

LinkBuy

18. Optionroom (ROOM)

DescribeWebsiteExchange

OptionRoom (ROOM) is an oracle as a service (OaaS) and a forecast protocol built on Polkadot, where governance solves the oracle requests. The protocol allows users to create and participate in events where governance consensus pegs the derivates of the events with real-world outcomes.

Pegging means to control the currency of an asset with the real-world currency of a country. When a user opts for an oracle request, they pay a fee. 

LinkBuy

19. Witnet (WIT)

DescribeWebsiteExchange

The Witnet protocol enables smart contracts to realize their true potential by giving them access to all sorts of valuable data sets, and by attesting and delivering that information securely thanks to its strong cryptoeconomic guarantees.

Being based on its own blockchain, Witnet is connected to multiple smart contract platforms through the use of bridges.

The Witnet blockchain is a single-purpose blockchain that has been built from scratch using the Rust programming language to address the particularities of the “oracle” use case (reliable and secure data providing).

LinkBuy

20. Ares protocol (ARES)

DescribeWebsiteExchange

Ares is an on-chain verifying oracle protocol powered by Polkdot. It provides reliable off-chain data efficiently and in a trustless manner.

Ares is built on Substrate and constructed as a parachain to link to Polkadot's ecology and share its security consensus. It is a scalable oracle network that provides decentralized data services to the Polkadot ecosystem and its parachains.

LinkBuy

How and Where to Buy oracle Tokens?

You will have to first buy one of the major cryptocurrencies, usually either Bitcoin (BTC), Ethereum (ETH), Tether (USDT), Binance (BNB)…

We will use Binance Exchange here as it is one of the largest crypto exchanges that accept fiat deposits.

Once you finished the KYC process. You will be asked to add a payment method. Here you can either choose to provide a credit/debit card or use a bank transfer, and buy one of the major cryptocurrencies, usually either Bitcoin (BTC), Ethereum (ETH), Tether (USDT), Binance (BNB)…

☞ SIGN UP ON BINANCE

Once finished you will then need to make a BTC/ETH/USDT/BNB deposit to the exchange from Binance depending on the available market pairs. After the deposit is confirmed you may then purchase Coin/Token from the Binance exchange.

Read more: Top 20 Media Cryptocurrencies

Thank you for reading! Don't forget to leave a like, comment and sharing it with others.

#blockchain #cryptocurrency #bitcoin #oracle 

Top Oracle Crypto Projects | Crypto Oracles Services

How to Create a Database Web App with Oracle APEX

In this tutorial, you'll learn how to create a database web app with Oracle APEX. Build scalable, secure enterprise apps with Oracle APEX

Oracle Application Express (APEX) is a low-code development platform that enables you to build scalable, secure enterprise apps, with world-class features, that can be deployed anywhere.

Using APEX, developers can quickly develop and deploy compelling apps that solve real problems and provide immediate value. You won't need to be an expert in a vast array of technologies to deliver sophisticated solutions. Focus on solving the problem and let APEX take care of the rest.

If you have Oracle Database, you already have Oracle APEX? It's one of the most popular features of Oracle Database — the most complete, integrated, and secure database solution for any scale deployment. This solid foundation enables apps built using Oracle APEX to be enterprise ready from day one.

Oracle APEX has been an included no-cost feature of Oracle Database since 2004. That means, if you have Oracle Database, you already have Oracle APEX! This also means there are no additional licensing fees irrespective of the number of developers, building any number of apps, for unlimited end users.

Oracle APEX runs anywhere that Oracle Database runs, whether it is on premises, in Oracle Cloud, or anywhere else.

Oracle Application Express (APEX) is a low-code development platform that enables you to build stunning, scalable, secure apps with world-class features that can be deployed anywhere. Using APEX, developers can quickly develop and deploy compelling apps that solve real problems and provide immediate value.

What you’ll learn:

  •        Setup Oracle Database
  •        Unlock Sample Schema
  •        Create a workspace in Oracle APEX
  •        Build a database driven web app
  •        Publish app to end users
  •        Perform CRUD Operations

Are there any course requirements or prerequisites?

  •        Basic knowledge of database concepts advised.

Who this course is for:

  •        Beginners to Oracle Application Development

#database #webapp #oracle

How to Create a Database Web App with Oracle APEX

How to Connect to Oracle Database from Python with cx_Oracle

Connect, fetch, insert, update, delete rows from Oracle database from python using cx_Oracle python module

00:00 - Intro
00:16 - Install cx_Oracle
00:44 - About Oracle Instant client
01:11 - Database Connection parameters
02:18 - Connect Oracle with sql developer
03:30 - cx_oracle connect to database
06:33 - Create sample table
08:07 - insert rows example
10:56 - parameter substitution
13:36 - executemany
15:01 - delete rows example
17:30 - cursor.rowcount example
19:15 - update rows example
21:37 - fetch rows example
24:38 - convert fetched rows to dataframe
25:40 - cursor.description to get fetched column names
26:59 - Recap
27:20 - Outro

Blog post for this video - https://nagasudhir.blogspot.com/2022/01/cxoracle-python-module-for-oracle.html 

sqldeveloper download link - https://www.oracle.com/tools/downloads/sqldev-downloads.html 

Subscribe: https://www.youtube.com/channel/UC-n1jHvAn9BZGFM99GwsQTg/featured 

#python #oracle 

How to Connect to Oracle Database from Python with cx_Oracle

Top Oracle Crypto Tokens

Oracle crypto projects solve real-world problems of blockchain and smart contracts. They allow on-chain smart contracts to get reliable off-chain data, often necessary for contract execution.

An oracle sources reliable data from multiple independent sources, filters it for inaccuracies, and transmits it across. It also ensures that data isn’t tampered with while delivering it to where it’s required.

In this article you will see Top 20 Oracle Crypto Tokens by Volume. 

Let’s check ☞

1. Chainlink - LINK

DescribePrice overviewWebsite

Founded in 2017, Chainlink is a blockchain abstraction layer that enables universally connected smart contracts. Through a decentralized oracle network, Chainlink allows blockchains to securely interact with external data feeds, events and payment methods, providing the critical off-chain information needed by complex smart contracts to become the dominant form of digital agreement.

The Chainlink Network is driven by a large open-source community of data providers, node operators, smart contract developers, researchers, security auditors and more. The company focuses on ensuring that decentralized participation is guaranteed for all node operators and users looking to contribute to the network.

Buy LINK
Link

2. WINkLink - WIN

DescribePrice overviewWebsite

WINkLink is the first decentralized oracle on the TRON network, which aims to integrate the real world with the blockchain space. The project aims to provide reliable data feeds to enable smart contract execution. WINklink Oracle allows developers to connect to any real-world data, and connect smart contracts with the real-world data feeds.

WIN is the native utility token of the platform, and has the following use cases:

Node incentives: Nodes that provide reliable, trusted data will be rewarded with WIN tokens.

Network payment: Developers will pay nodes with WIN tokens to request for trusted data.

WIN token is a TRC-20 token running on the TRON network. WIN tokens are used to incentivize participation from developers and nodes.

 

Buy WIN
Link

3. Band Protocol - BAND

DescribePrice overviewWebsite

Band Protocol is a cross-chain data oracle platform that is able to take real-world data and supply it to on-chain applications, while also connecting APIs to smart-contracts to facilitate the exchange of information between on-chain and off-chain data sources.

By supplying reputable, verifiable real-world data to blockchains, Band Protocol unlocks a range of new use cases for developers to explore — since they can now use any type of real-world data as part of their decentralized application (DApp) logic, including sports, weather, random numbers, price feed data and more.

BAND is the native token of the Band Protocol ecosystem and is used as collateral by validators involved in fulfilling data requests, as well as the main medium of exchange on BandChain — being used to paying for private data.

Buy BAND
Link

4. UMA - UMA

DescribePrice overviewWebsite

UMA is an optimistic oracle (OO) that can record any verifiable truth onto a blockchain. The OO has been called “a human-powered truth machine” because it is flexible enough to handle ambiguity and expands the design space possible in web3.

Oracles are a key part of blockchain infrastructure. They enable communication between the external world and on-chain environments in a trustless manner. Oracles are vital for many parts of the blockchain industry including decentralized finance (DeFi) and Web3 applications.

An optimistic oracle like UMA's uses a “true unless disputed” pattern, with a tokenholder vote to resolve disputes. Anyone can propose an answer to a data request, and it is accepted as true if it is not disputed during a verification period. The “optimistic” design differs from a price-feed oracle, where prices are streamed on-chain and are instantly final.

Buy UMA
Link

5. Tellor - TRB

DescribePrice overviewWebsite

Tellor is a decentralized oracle protocol.

Tellor’s oracle supplies data that can be requested, validated and put on-chain permissionlessly with data reporters competing for incentives of TRB. Data reporters bring valuable information on-chain for a wide range of DeFi applications.

Tellor’s oracle works by incentivizing data reporters to put valid data on-chain while also disincentivizing bad reports via disputes and slashing. Becoming a reporter requires no verification process i.e. permissionless. Anyone anywhere in the world can be a reporter using open source software, a unique characteristic among blockchain oracles.

When oracle users request the value of an off-chain data point (e.g. BTC/USD), data reporters compete to add this value to an on-chain data-bank, accessible by all smart contracts on the networks Tellor supports (Ethereum, Polygon, Algorand, etc.) The frequency with which data can be updated is limited only by how much / how often users “tip” the feed with TRB.

Buy TRB
Link

6. API3 - API3

DescribePrice overviewWebsite

Smart contracts often struggle to access dependable data, but application programming interfaces (APIs) have been touted as a solution to this problem.

API3’s stated goal is to allow decentralized versions of APIs to be built, managed and monetized at scales.

Oracles are a form of middleware that sit in between APIs and smart contracts — increasing costs and centralization. API3 intends to get around this problem by enabling API providers to operate their very own nodes.

API3’s token went live at the start of December following on from a token sale that generated tens of millions of dollars.

Buy API3
Link

7. NEST Protocol - NEST

DescribePrice overviewWebsite

NEST Protocol is the stochastic computer based on PVM, enables the generation and programming of stochastic assets.

NEST Protocol creatively introduces random information flow with a truely decentralized oracle, NEST Oracle. And it tokenizes random information flow through the OMM mechanism, generating many stochastic assets. PVM , based on basic functions, can program stochastic assets, which applies to a large number of real-world scenarios.

An inherent cost mechanism ensures the system supply converges, resulting in a new universal coin with an innate price appreciation logic. The NEST coin provides a whole new development tool and is a creative new asset for the blockchain world.

Buy NEST
Link

8. iExec RLC - RLC

DescribePrice overviewWebsite

iExec is the leading provider of blockchain-based decentralized computing. Blockchain is utilized to organize a market network where people can monetize their computing power as well as applications and even datasets.

It does this by providing on-demand access to cloud computing resources. IExec can support applications in fields such as big data, healthcare, AI, rendering and fintech. 

Buy RLC
Link

9. Augur - REP

DescribePrice overviewWebsite

Augur is an oracle network and peer-to-peer powered prediction market protocol and is decentralized in nature. Augur is based on a set of smart contracts designed for usage on the Ethereum network.

Blockchain oracles are things that connect blockchains to external systems, allowing smart contracts to execute depending on real-world inputs and outputs.

Smart contracts are similar to ordinary contracts, except instead of being written on paper, these contracts run as protocols on the blockchain. Augur is distinguished by its decentralized governance mechanism and open-source contracts, which enable all users to participate in fair speculation.

Buy REP
Link

10. Skey Network - SKEY

DescribePrice overviewWebsite

Skey Network is the world’s first platform to successfully bridge decentralized finance (DeFi) and IoT, and will create the platform for a new economy of physical assets called the ‘Blockchain of Things’ (BoT). Our decentralized network of blockchain oracles connects the on-chain world of digital assets, smart contracts, and DeFi with off-chain data, services, and devices.

The non-fungibility (i.e. uniqueness) property of Skey Network NFTs is also a game-changer when applied to IoT. Using a Skey Network NFT, every smart object in a network can have its own unique token providing proof of ownership. Cars, keys, doors, gates, and locker systems can all have their own unique token — boosted with the Skey Network NFT functionalities.

Buy SKEY
Link

11. Diadata - DIA

DescribePrice overviewWebsite

DIA (Decentralised Information Asset) is an open-source oracle platform that enables market actors to source, supply and share trustable data. DIA aims to be an ecosystem for open financial data in a financial smart contract ecosystem, to bring together data analysts, data providers and data users.

In general, DIA provides a reliable and verifiable bridge between off-chain data from various sources and on-chain smart contracts that can be used to build a variety of financial DApps.

The DIA governance token will be used to fund data collection, data validation, voting on governance decisions and to incentivize the development of the platform. Users can stake DIA tokens to incentivi`e new data to appear on the platform, but access to historical data though DIA is free.

Buy DIA
Link

12. Oraichain  - ORAI

DescribePrice overviewWebsite
As an AI Layer 1 for Data Economy and Oracle services, Oraichain is the world's first intelligent and secure solutions for emerging Web3, scalable Dapps, and decentralized AI.
 
Buy ORAI
Link

13. Razor Network - RAZOR

DescribePrice overviewWebsite

Razor Network is a decentralized oracle network that connects smart contracts with real-world, off-chain data in a quick, robust and secure way.

Razor Network focuses on economic security, decentralization, protecting stakers from different vectors of attack and protecting clients from malicious stakers. It also offers ease of use for developers and collusion, censorship and bribing resistance.

RAZOR is the protocol’s native utility token that can be used to pay frees, stake and vote. Staking RAZOR as a user involves the processing of data requests and reporting of information to the network. When staked, RAZOR tokens get locked into a smart contract.

Buy RAZOR
Link

14. Umbrella Network - UMB

DescribePrice overviewWebsite

The Umbrella Network launched one of the largest initial dex offerings (IDOs) at the beginning of 2021. This is a community-owned, decentralized oracle service providing secure and extensively scalable data solutions for decentralized finance (DeFi) applications.

Umbrella provides access to revolutionary financial datasets for blockchain app developers in the crypto space as well as those with an interest in real-world business transactions.

The decentralization power of the Umbrella Network is centered around the UMB utility token, which is used for staking, community votes and rewards and incentives. By introducing a layer two blockchain integration, Umbrella Network creates a highly scalable oracle solution.

Buy UMB
Link

15. HAPI Protocol - HAPI

DescribePrice overviewWebsite

HAPI is a one-of-a-kind decentralized security protocol that prevents and interrupts any potential malicious activity within the blockchain space. HAPI works by leveraging both external and off-chain data as well as on-chain data accrued directly by HAPI and is publicly available.

One can imagine HAPI being an all-encompassing, overarching protocol that combines crypto intelligence data from multiple sources allowing the most accurate information on malicious activity, and compromised wallets.

HAPI is the only crypto cybersecurity solution that can be integrated into DEXes and DeFi protocols preventing Money Laundering by embedding Smart Contracts and routing each transaction through it.


 

Buy HAPI
Link

How and Where to Buy Oracle Crypto Tokens?

You will have to first buy one of the major cryptocurrencies, usually either Bitcoin (BTC), Ethereum (ETH), Tether (USDT), Binance (BNB)…

We will use Binance Exchange here as it is one of the largest crypto exchanges that accept fiat deposits.

Once you finished the KYC process. You will be asked to add a payment method. Here you can either choose to provide a credit/debit card or use a bank transfer, and buy one of the major cryptocurrencies, usually either Bitcoin (BTC), Ethereum (ETH), Tether (USDT), Binance (BNB)…

☞ SIGN UP ON BINANCE

Once finished you will then need to make a BTC/ETH/USDT/BNB deposit to the exchange from Binance depending on the available market pairs. After the deposit is confirmed you may then purchase Coin/Token from the Binance exchange.

🔥 If you’re a beginner. I believe the article below will be useful to you ☞ Research Cryptocurrency Before Investing in 5 Basic Steps

DISCLAIMER: The Information in the post isn’t financial advice, is intended FOR GENERAL INFORMATION PURPOSES ONLY. Trading Cryptocurrency is VERY risky. Make sure you understand these risks and that you are responsible for what you do with your money.

Thank you for reading !

#blockchain #bitcoin #cryptocurrency #oracle 

Top Oracle Crypto Tokens
Zachary Palmer

Zachary Palmer

1664788839

Oracle Cloud Infrastructure Tutorial for Beginners

Learn the fundamentals of Oracle Cloud Infrastructure (OCI). Build and manage scalable and highly available infrastructure in OCI

You'll learn:

  • OCI concepts and terminology
  • Identity and Access Management
  • Create and secure Virtual Cloud Networks
  • Configure OCI Load Balancer as a Service

Oracle Cloud for Infrastructure, one of the fastest growing enterprise-grade cloud providers in the Industry, and is THE leading cloud provider for companies who trust their data and workloads to run on Oracle Database.

No longer just a Database Company, Oracle has transformed into a true cloud-native open-standards leader.

This course teaches students about the core infrastructure services needed to run any workload in the cloud, including virtual networking, compute, storage, and security in the realm of OCI

In this course, students will sign up for an Oracle Cloud account and take advantage of the free trial period and credits. Students will obtain real-world hands-on experience provisioning virtual networks, compute instances, block and object storage buckets, and load balancers, all with a focus on security and building scalable environments.

OCI Free Tier and Credits

New customers to OCI can take advantage of free credits and a tier of infrastructure services that are always free, even after your trial period expires.

This course uses Always Free Tier services whenever possible to help students keep their OCI learning costs down.

In-Depth Lectures

Each lecture provides a detailed look at the core infrastructure services that matter most to users, including Compute, Storage, and Networking.

Hands-On Exercises

Practical Guide to OCI provides students with a comprehensive lab guide that walks the student through each of the core OCI infrastructures. Students will learn how to create and manage OCI resources and implement security using a variety of OCI tools.

Requirements

  •    Ability to sign up for an Oracle Cloud Infrastructure account using a Credit Card or access to an existing Account.

Who this course is for:

  •    System Administrators, DevOps, Engineers, Developers

#oracle #cloud #database

Oracle Cloud Infrastructure Tutorial for Beginners
Charles Cooper

Charles Cooper

1664773022

Oracle Database Performance Tuning

In this course you will learn about the fundamentals concepts and terms about tuning and troubleshooting Oracle Databases. 

Requirements

  •    Oracle Database Architecture knowledge

Who this course is for:

  •    Anyone interested to troubleshoot and tune an Oracle database


#oracle #database 

Oracle Database Performance Tuning
Debbie Clay

Debbie Clay

1664259135

Deploy Oracle Database on Docker

Learn the complete configuration of the Oracle Database Enterprise edition in Docker. Oracle Instance - access it within the container and outside container, install ODBC driver, configure DSN

Starting from Installing and configuring the Docker desktop. There are 2 types of backends for the docker desktop to run. One is the Hyper-V and the other is the WSL2  backend. In this course, the Hyper-V backend is enabled.


You'll learn:

  • Setup Oracle enterprise database in windows using Docker
  • ODBC driver configuration to connect to Oracle DB
  • DSN configuration

The 2 versions of Oracle instances are created in docker, one with port mapping and the other without that. The other applications or tools can connect to the oracle instance only if the port mapping is enabled for that container. The steps are explained to install Oracle ODBC driver in windows. The ODBC Driver for Oracle enables an application to access data in an Oracle database through the ODBC interface. Any application, it can be java or DOTnet application, wants to connect to Oracle instance and do the database operations, can use DSN to connect to Database. The steps to configure DSN in windows are explained here.

The external tool SQL developer is used to connect the databases hosted in Docker.  Performed the SQL operations in the SQL editor. Created a new user in the Oracle instance and the same user is used to connect to the Oracle instance from ODBC data source and from SQL developer. Modified the user password and verified.

Requirements

  •    Basics of Docker desktop

Who this course is for:

  •    Application Developers and the administrators

#oracle #docker #database

Deploy Oracle Database on Docker
Louis Jones

Louis Jones

1660965436

A Beginner's Guide to RDBMS (Relational Database Management System)

What is a Relational Database Management System (RDBMS)? Learn about RDBMS and the language used to access large datasets – SQL.

RDBMS is an acronym for Relational Database Management System and is a type of database management system that stores data in a structured format using rows and columns, making it easy to locate and access data in relation to another piece of data in the database.

What is a Database?

A database is a set of data stored in a computer. This data is usually structured in a way that makes the data easily accessible.
 

What is a Relational Database?

A relational database is a type of database. It uses a structure that allows us to identify and access data in relation to another piece of data in the database. Often, data in a relational database is organized into tables.
 

Tables: Rows and Columns

Tables can have hundreds, thousands, sometimes even millions of rows of data. These rows are often called records.

Tables can also have many columns of data. Columns are labeled with a descriptive name (say, age for example) and have a specific data type.

For example, a column called age may have a type of INTEGER (denoting the type of data it is meant to hold).

Table

In the table above, there are three columns (name, age, and country).

The name and country columns store string data types, whereas age stores integer data types. The set of columns and data types make up the schema of this table.

The table also has four rows, or records, in it (one each for Natalia, Ned, Zenas, and Laura).
 

What is a Relational Database Management System (RDBMS)?

A relational database management system (RDBMS) is a program that allows you to create, update, and administer a relational database. Most relational database management systems use the SQL language to access the database.
 

What is SQL?

SQL (Structured Query Language) is a programming language used to communicate with data stored in a relational database management system. SQL syntax is similar to the English language, which makes it relatively easy to write, read, and interpret.

Many RDBMSs use SQL (and variations of SQL) to access the data in tables. For example, SQLite is a relational database management system. SQLite contains a minimal set of SQL commands (which are the same across all RDBMSs). Other RDBMSs may use other variants.

(SQL is often pronounced in one of two ways. You can pronounce it by speaking each letter individually like “S-Q-L”, or pronounce it using the word “sequel”.)
 

Popular Relational Database Management Systems

SQL syntax may differ slightly depending on which RDBMS you are using. Here is a brief description of popular RDBMSs:
 

MySQL

MySQL is the most popular open source SQL database. It is typically used for web application development, and often accessed using PHP.

The main advantages of MySQL are that it is easy to use, inexpensive, reliable (has been around since 1995), and has a large community of developers who can help answer questions.

Some of the disadvantages are that it has been known to suffer from poor performance when scaling, open source development has lagged since Oracle has taken control of MySQL, and it does not include some advanced features that developers may be used to.
 

PostgreSQL

PostgreSQL is an open source SQL database that is not controlled by any corporation. It is typically used for web application development.

PostgreSQL shares many of the same advantages of MySQL. It is easy to use, inexpensive, reliable and has a large community of developers. It also provides some additional features such as foreign key support without requiring complex configuration.

The main disadvantage of PostgreSQL is that it can be slower in performance than other databases such as MySQL. It is also slightly less popular than MySQL.

For more information about PostgreSQL including installation instructions, read this article.

Oracle DB

Oracle Corporation owns Oracle Database, and the code is not open sourced.

Oracle DB is for large applications, particularly in the banking industry. Most of the world’s top banks run Oracle applications because Oracle offers a powerful combination of technology and comprehensive, pre-integrated business applications, including essential functionality built specifically for banks.

The main disadvantage of using Oracle is that it is not free to use like its open source competitors and can be quite expensive.
 

SQL Server

Microsoft owns SQL Server. Like Oracle DB, the code is close sourced.

Large enterprise applications mostly use SQL Server.

Microsoft offers a free entry-level version called Express but can become very expensive as you scale your application.
 

SQLite

SQLite is a popular open source SQL database. It can store an entire database in a single file. One of the most significant advantages this provides is that all of the data can be stored locally without having to connect your database to a server.

SQLite is a popular choice for databases in cellphones, PDAs, MP3 players, set-top boxes, and other electronic gadgets. The SQL courses on Codecademy use SQLite.

Conclusion

Relational databases store data in tables. Tables can grow large and have a multitude of columns and records. Relational database management systems (RDBMSs) use SQL (and variants of SQL) to manage the data in these large tables. The RDBMS you use is your choice and depends on the complexity of your application.

Original article source at https://www.codecademy.com

#database #sql #sqlite #mysql #postgresql #oracle #sqlserver

A Beginner's Guide to RDBMS (Relational Database Management System)
Best of Crypto

Best of Crypto

1660224000

Fantom Oracle Backend Service Built on Golang

The repository contains implementation of high performance blockchain backend service for oracle contracts off-chain world interaction.

The Oracle Backend service is responsible for monitoring oracle smart contracts activity on block chain, especially for emitted events on contracts, and respond with relevant data from off-chain world needed to perform on-chain actions. Special modules can also feed on-chain contracts with external data, based on specified criteria, timer, or API response.

Building the source

Building Oracle Backend requires GIT package and Go (version 1.14 or later is recommended). You can install it using your favourite package manager. The latest version of Go can be installed directly from GoLang Website.

Once you have the Go environment ready, clone the Watchdog repository from GitHub and build the binary package:

git clone https://github.com/Fantom-foundation/Fantom-Oracle-Backend.git
go build -o ./build/oracle ./cmd/oracle

The build output is build/watchdog executable.

You don't need to clone the project into $GOPATH due to Go Modules tooling, use any suitable location. We recommend moving the built Oracle Backend binary to your bin path and using Systemd unit to manage the Backend as a service for production use.

Running the Oracle Backend server

You need access to an RPC interface of an Opera Lachesis node to run the Oracle Backend server. Please follow Lachesis instructions to build and run the node. You can obtain access to a remotely running instance of Lachesis, too.

We recommend using local IPC channel for communication between a Lachesis node and the Oracle Backend server for performance and security reasons. Please consider security implications of opening Lachesis RPC to outside world access.

System.d Service unit file

To run the Oracle Backend as a system service on Linux, create a service unit file on appropriate location. The actual place for putting the service file may vary by Linux distribution. For example, you can use /etc/systemd/system/oracle.service file path on Ubuntu systems.

We assume you want to use /var/opera/oracle as the working directory for the Watchdog and that you copied the Watchdog binary to /usr/bin/oracle. In that case, the recommended .service file content is:

[Unit]
Description=Fantom Oracle Backend service
After=network.target auditd.service

[Service]
Type=simple
User=opera
Group=opera
WorkingDirectory=/var/opera/oracle
ExecStart=/usr/bin/oracle \
            --rpc /var/opera/lachesis/data/lachesis.ipc \
            --cfg /var/opera/oracle/modules.json \
            --log NOTICE
OOMScoreAdjust=-900
Restart=on-failure
RestartSec=5s

[Install]
WantedBy=multi-user.target
Alias=oracle.service

Adjust the service unit file to match your path and configuration details for Opera RPC interface, work path and Oracle Backend binary file location.

Don't forget to update the System.d status to be able to use the new service file to start and stop the Watchdog: systemctl daemon-reload. Manage the service start/stop using usual System.d commands, i.e. systemctl start oracle.service.

Download details:

Author: Fantom-foundation
Source code: https://github.com/Fantom-foundation/Fantom-Oracle-Backend
License: MIT license

#fantom #blockchain #oracle #go #golang

Fantom Oracle Backend Service Built on Golang
Best of Crypto

Best of Crypto

1660209300

Fantom Oracle Price Feed Contract Written in Solidity

The repository contains Solidity smart contract implementing simplified price feeds oracle for Fantom Opera network.

A deployed smart contract offers price exachange pair values indexed and identified by exchange symbols. The actual price is fed into the contract from an external off-chain data source. The backend service implementing this function is available on the foundation GitHub as the Fantom Oracle Backend.

Contract compilation

Install appropriate Solidity compiler. The contract expects Solidity version to be from the branch 0.5.0. The latest available Solidity compiler of this branch is the Solidity Version 0.5.17.

Compile the contract for deployment.

solc -o ./build --optimize --optimize-runs=200 --abi --bin ./contract/PriceOracle.sol

Deploy compiled binary file ./build/FantomBallot.bin into the blockchain.

Use generated ABI file ./build/FantomBallot.abi to interact with the contract.

A simple deployment script supported by Web3 library is available in the deployment folder. Use NPM to install dependecies using npm install and node.js to run the deployment script. Please make sure to set internal variables to your liking.

Download details:

Author: Fantom-foundation
Source code: https://github.com/Fantom-foundation/Fantom-Oracle-Pricefeed
License: MIT license

#fantom #blockchain #oracle #solidity #smartcontract

Fantom Oracle Price Feed Contract Written in Solidity
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1659533700

Chainlink: Node Of The Decentralized Oracle Network & Off-chain

Chainlink 

Chainlink expands the capabilities of smart contracts by enabling access to real-world data and off-chain computation while maintaining the security and reliability guarantees inherent to blockchain technology.

This repo contains the Chainlink core node, operator UI and contracts. The core node is the bundled binary available to be run by node operators participating in a decentralized oracle network. All major release versions have pre-built docker images available for download from the Chainlink dockerhub. If you are interested in contributing please see our contribution guidelines. If you are here to report a bug or request a feature, please check currently open Issues. For more information about how to get started with Chainlink, check our official documentation. Resources for Solidity developers can be found in the Chainlink Hardhat Box.

Community

Chainlink has an active and ever growing community. Discord is the primary communication channel used for day to day communication, answering development questions, and aggregating Chainlink related content. Take a look at the community docs for more information regarding Chainlink social accounts, news, and networking.

Build Chainlink

  1. Install Go 1.18, and add your GOPATH's bin directory to your PATH
    • Example Path for macOS export PATH=$GOPATH/bin:$PATH & export GOPATH=/Users/$USER/go
  2. Install NodeJS & Yarn. See the current version in package.json at the root of this repo under the engines.node key.
    • It might be easier long term to use nvm to switch between node versions for different projects. For example, assuming $NODE_VERSION was set to a valid version of NodeJS, you could run: nvm install $NODE_VERSION && nvm use $NODE_VERSION
  3. Install Postgres (>= 11.x).
    • You should configure Postgres to use SSL connection (or for testing you can set ?sslmode=disable in your Postgres query string).
  4. Ensure you have Python 3 installed (this is required by solc-select which is needed to compile solidity contracts)
  5. Download Chainlink: git clone https://github.com/smartcontractkit/chainlink && cd chainlink
  6. Build and install Chainlink: make install
    • If you got any errors regarding locked yarn package, try running yarn install before this step
    • If yarn install throws a network connection error, try increasing the network timeout by running yarn install --network-timeout 150000 before this step
  7. Run the node: chainlink help

For the latest information on setting up a development environment, see the Development Setup Guide.

Mac M1/ARM64 [EXPERIMENTAL]

Chainlink can be experimentally compiled with ARM64 as the target arch. You may run into errors with cosmwasm:

# github.com/CosmWasm/wasmvm/api
ld: warning: ignoring file ../../../.asdf/installs/golang/1.18/packages/pkg/mod/github.com/!cosm!wasm/wasmvm@v0.16.3/api/libwasmvm.dylib, building for macOS-arm64 but attempting to link with file built for macOS-x86_64
Undefined symbols for architecture arm64:# github.com/CosmWasm/wasmvm/api
ld: warning: ignoring file ../../../.asdf/installs/golang/1.18/packages/pkg/mod/github.com/!cosm!wasm/wasmvm@v0.16.3/api/libwasmvm.dylib, building for macOS-arm64 but attempting to link with file built for macOS-x86_64
Undefined symbols for architecture arm64:

In this case, try the following steps:

  1. git clone git@github.com:mandrean/terra-core.git
  2. cd terra-core; git checkout feat/multiarch
  3. make install; cd ..
  4. go work init /path/to/chainlink
  5. go work use /path/to/terra-core

Ethereum Node Requirements

In order to run the Chainlink node you must have access to a running Ethereum node with an open websocket connection. Any Ethereum based network will work once you've configured the chain ID. Ethereum node versions currently tested and supported:

[Officially supported]

[Unofficially supported]

We cannot recommend specific version numbers for ethereum nodes since the software is being continually updated, but you should usually try to run the latest version available.

Running a local Chainlink node

NOTE: By default, chainlink will run in TLS mode. For local development you can disable this by setting the following env vars:

CHAINLINK_DEV=true
CHAINLINK_TLS_PORT=0
SECURE_COOKIES=false

Alternatively, you can generate self signed certificates using tools/bin/self-signed-certs or manually.

To start your Chainlink node, simply run:

chainlink node start

By default this will start on port 6688. You should be able to access the UI at http://localhost:6688/.

Chainlink provides a remote CLI client as well as a UI. Once your node has started, you can open a new terminal window to use the CLI. You will need to log in to authorize the client first:

chainlink admin login

(You can also set ADMIN_CREDENTIALS_FILE=/path/to/credentials/file in future if you like, to avoid having to login again).

Now you can view your current jobs with:

chainlink jobs list

To find out more about the Chainlink CLI, you can always run chainlink help.

Check out the doc pages on Jobs to learn more about how to create Jobs.

Configuration

Node configuration is managed by a combination of environment variables and direct setting via API/UI/CLI.

Check the official documentation for more information on how to configure your node.

External Adapters

External adapters are what make Chainlink easily extensible, providing simple integration of custom computations and specialized APIs. A Chainlink node communicates with external adapters via a simple REST API.

For more information on creating and using external adapters, please see our external adapters page.

Development

Running tests

Install Yarn

Install gencodec and jq to be able to run go generate ./... and make abigen

Install mockery

make mockery

Using the make command will install the correct version.

  1. Build contracts:
yarn
yarn setup:contracts

2.   Generate and compile static assets:

go generate ./...

3.   Prepare your development environment:

export DATABASE_URL=postgresql://127.0.0.1:5432/chainlink_test?sslmode=disable

Note: Other environment variables should not be set for all tests to pass

4.   Drop/Create test database and run migrations:

go run ./core/main.go local db preparetest

If you do end up modifying the migrations for the database, you will need to rerun

5.   Run tests:

go test ./...

Notes

  • The parallel flag can be used to limit CPU usage, for running tests in the background (-parallel=4) - the default is GOMAXPROCS
  • The p flag can be used to limit the number of packages tested concurrently, if they are interferring with one another (-p=1)
  • The -short flag skips tests which depend on the database, for quickly spot checking simpler tests in around one minute

Race Detector

As of Go 1.1, the runtime includes a data race detector, enabled with the -race flag. This is used in CI via the tools/bin/go_core_race_tests script. If the action detects a race, the artifact on the summary page will include race.* files with detailed stack traces.

It will not issue false positives, so take its warnings seriously.

For local, targeted race detection, you can run:

GORACE="log_path=$PWD/race" go test -race ./core/path/to/pkg -count 10
GORACE="log_path=$PWD/race" go test -race ./core/path/to/pkg -count 100 -run TestFooBar/sub_test 

https://go.dev/doc/articles/race_detector

Fuzz tests

As of Go 1.18, fuzz tests func FuzzXXX(*testing.F) are included as part of the normal test suite, so existing cases are executed with go test.

Additionally, you can run active fuzzing to search for new cases:

go test ./pkg/path -run=XXX -fuzz=FuzzTestName

https://go.dev/doc/fuzz/

Solidity

Inside the contracts/ directory:

  1. Install dependencies:
yarn

2.  Run tests:

yarn test

Code Generation

Go generate is used to generate mocks in this project. Mocks are generated with mockery and live in core/internal/mocks.

Nix Flake

A flake is provided for use with the Nix package manager. It defines a declarative, reproducible development environment.

To use it:

  1. Nix has to be installed with flake support.
  2. Run nix develop. You will be put in shell containing all the dependencies. Alternatively, a direnv integration exists to automatically change the environment when cd-ing into the folder.
  3. Create a local postgres database:
cd $PGDATA/
initdb
pg_ctl -l $PGDATA/postgres.log -o "--unix_socket_directories='$PWD'" start
createdb chainlink_test -h localhost
createuser --superuser --no-password chainlink -h localhost

4.   Start postgres, pg_ctl -l $PGDATA/postgres.log -o "--unix_socket_directories='$PWD'" start

Now you can run tests or compile code as usual.

Tips

For more tips on how to build and test Chainlink, see our development tips page.

Contributing

Chainlink's source code is licensed under the MIT License, and contributions are welcome.

Please check out our contributing guidelines for more details.

Thank you!

Download details:

Author: smartcontractkit
Source code: https://github.com/smartcontractkit/chainlink
License: MIT license

#smartcontract #blockchain #oracle #chainlink #golang #solidity

Chainlink: Node Of The Decentralized Oracle Network & Off-chain