Edison  Stark

Edison Stark

1596489300

What is the difference between relational and non-relational databases?

OK, so we know you’re here to weigh the technical differences between the relational and non-relational databases. But before we dive in, we need to define some important details. You need to determine what priority scalability represents for your particular model.

To make your data model as accurate as possible, you need to ask the right questions. Otherwise, your solution may not be the most appropriate for your problem. If you already have this well defined, go ahead.

Table of Contents

What is a relational database?

relational database is a digital database based on the relational data model as proposed by E. F. Codd in 1970, an intuitive and direct way to represent data in tables. Relational databases store and provide access to data points that are related to each other.

UML-Relational database example

In a relational database, each table row is a record with a unique identification called a primary key. The table columns contain the data attributes, and each record usually has a value for each attribute, making it easier to establish the relationships between the data. In this example below the Primary Key is the **id**.

banco de dados relacional - tabela exemplo

There are several systems you can use to manage relational databases, they are known as Relational Database Management Systems (DBMS). The most popular among them is MySQL, but we also have other options like Oracle Database, Microsoft SQL Server, and IBM DB2.

The vast majority of RDBMS offer the option to use SQL (Structured Query Language) for database query and maintenance.

Types of relationship

One of the advantages of a relational database is that once you have your data kept in clearly defined tables you can connect or relate the data between different tables. In order to identify these relationships, you need to examine the data and have an understanding of the business rules that apply to the data and tables.

When creating relationships, you always work with two tables at a time. One table is called the main table or parent table and the other is the related table or child table.

The three types of relationships you will find in the relational databases are, one-to-one, one-to-many, and many-to-many. The relationships are described below.

  • One-to-one (1…1): Both tables can have only one record on each side of the relationship. Each primary table value refers to only one (or no) record in the related table.
  • One-to-many (1…n): The primary table contains only one record that can relate to none, one, or many records in the related table.
  • Many-to-many (n…n): Each record in both tables can relate to any number of records (or no records) in the other table. Many relationships of type n…n require a third table, known as a link table or associated table, because relational systems cannot directly accommodate the relationship.

#databases

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What is the difference between relational and non-relational databases?
Ruth  Nabimanya

Ruth Nabimanya

1623224340

Relational vs Non-Relational Databases

If we have a look at available databases, we see a clear line, drawn in the middle. On one side, relational systems like MySQL, PostgreSQL, or SQLite. On the other side, non-relational ones like MongoDB or Neo4j. In this article you will learn the difference between them and which ones, you should use when!

Relational data

Non-relational data

When to use what?

Can I mix multiple databases?

#engineering #database #nosql #coding #sql #relational vs non-relational databases

Ruth  Nabimanya

Ruth Nabimanya

1620633584

System Databases in SQL Server

Introduction

In SSMS, we many of may noticed System Databases under the Database Folder. But how many of us knows its purpose?. In this article lets discuss about the System Databases in SQL Server.

System Database

Fig. 1 System Databases

There are five system databases, these databases are created while installing SQL Server.

  • Master
  • Model
  • MSDB
  • Tempdb
  • Resource
Master
  • This database contains all the System level Information in SQL Server. The Information in form of Meta data.
  • Because of this master database, we are able to access the SQL Server (On premise SQL Server)
Model
  • This database is used as a template for new databases.
  • Whenever a new database is created, initially a copy of model database is what created as new database.
MSDB
  • This database is where a service called SQL Server Agent stores its data.
  • SQL server Agent is in charge of automation, which includes entities such as jobs, schedules, and alerts.
TempDB
  • The Tempdb is where SQL Server stores temporary data such as work tables, sort space, row versioning information and etc.
  • User can create their own version of temporary tables and those are stored in Tempdb.
  • But this database is destroyed and recreated every time when we restart the instance of SQL Server.
Resource
  • The resource database is a hidden, read only database that holds the definitions of all system objects.
  • When we query system object in a database, they appear to reside in the sys schema of the local database, but in actually their definitions reside in the resource db.

#sql server #master system database #model system database #msdb system database #sql server system databases #ssms #system database #system databases in sql server #tempdb system database

Ruth  Nabimanya

Ruth Nabimanya

1620663480

Which Database Is Right For You?Graph Database vs. Relational Database

At the very beginning of most development endeavors lies an important question: What database do I choose? There is such an abundance of database technologies at this moment, it’s no wonder many developers don’t have the time or energy to research new ones. If you are one of those developers and you aren’t very familiar with graph databases in general, you’ve come to the right place!

In this article, you will learn about the main differences between a graph database and a relational database, what kind of use-cases are best suited for each database type, and what are their strengths and weaknesses.

How Does a Graph Database Differ from a Relational Database?

The Graph Data Model

The Relational Data Model

When to use a Graph Database?

When not to use a Graph Database

Is a Graph Database Worth it?

#graph-database #relational-database #graph-theory #graph-analysis #data-analytics #networks #data #database

To Relational or Not to Relational?

Working on your next project but not sure which back-end technology to use? For starters, databases come in two flavors: relational and non-relational. Both have their own set of rules, pros and cons which help in determining which type of application they should be used in. Let us delve into these differences so that we would be able to decide which one is better suited for us.

Relational Databases:

Relational databases store data in the form of tables containing rows (representing entries) and columns (containing a set of information) having a unique key for each row. These keys can either be primary or foreign. It is based on a form of algebraic set theory known as relational algebra, which is used in the relational modeling of data. They are better suited for applications where many transactions are involved, also known as transactions-oriented applications (OLTP).

They use SQL (Structured Query Language) as a language for the maintenance and querying of databases. We can use MySQL, SQL Server, SQLite, MS Access, Oracle, Sybase, PostGreSQL, or Informix.

They are normalized databases i.e they are in accordance with a series of so-called “normal forms” in order to reduce data redundancy and improve data integrity.

Advantages:

  1. They are useful for applications requiring a lot of transactions, complex queries and routine analysis of data

  2. They are robust, simple, structured and flexible.

  3. They ensure reliable data transactions through ACID (Atomity, Consistency, Isolation, Durability).

  4. Easier to use because of GUI (Graphical User Interface)

Disadvantages:

  1. Their main disadvantage is that it is impossible to horizontally scale them. If our business requirements increase, then we need to move on to bigger systems, making them more costly in the long run.

  2. Images and other multimedia files cannot be stored.

  3. We cannot use them for geospatial data

  4. They can cause ORM Impedance Mismatch

Here_ is a basic CRUD demo of __MySQL _using Node.js. You need to install the relevant software before running the examples in the repository.

#non-relational-database #mysql #relational-databases #nodejs #mongodb

Django-allauth: A simple Boilerplate to Setup Authentication

Django-Authentication 

A simple Boilerplate to Setup Authentication using Django-allauth, with a custom template for login and registration using django-crispy-forms.

Getting Started

Prerequisites

  • Python 3.8.6 or higher

Project setup

# clone the repo
$ git clone https://github.com/yezz123/Django-Authentication

# move to the project folder
$ cd Django-Authentication

Creating virtual environment

  • Create a virtual environment for this project:
# creating pipenv environment for python 3
$ virtualenv venv

# activating the pipenv environment
$ cd venv/bin #windows environment you activate from Scripts folder

# if you have multiple python 3 versions installed then
$ source ./activate

Configured Enviromment

Environment variables

SECRET_KEY = #random string
DEBUG = #True or False
ALLOWED_HOSTS = #localhost
DATABASE_NAME = #database name (You can just use the default if you want to use SQLite)
DATABASE_USER = #database user for postgres
DATABASE_PASSWORD = #database password for postgres
DATABASE_HOST = #database host for postgres
DATABASE_PORT = #database port for postgres
ACCOUNT_EMAIL_VERIFICATION = #mandatory or optional
EMAIL_BACKEND = #email backend
EMAIL_HOST = #email host
EMAIL_HOST_PASSWORD = #email host password
EMAIL_USE_TLS = # if your email use tls
EMAIL_PORT = #email port

change all the environment variables in the .env.sample and don't forget to rename it to .env.

Run the project

After Setup the environment, you can run the project using the Makefile provided in the project folder.

help:
 @echo "Targets:"
 @echo "    make install" #install requirements
 @echo "    make makemigrations" #prepare migrations
 @echo "    make migrations" #migrate database
 @echo "    make createsuperuser" #create superuser
 @echo "    make run_server" #run the server
 @echo "    make lint" #lint the code using black
 @echo "    make test" #run the tests using Pytest

Preconfigured Packages

Includes preconfigured packages to kick start Django-Authentication by just setting appropriate configuration.

PackageUsage
django-allauthIntegrated set of Django applications addressing authentication, registration, account management as well as 3rd party (social) account authentication.
django-crispy-formsdjango-crispy-forms provides you with a crispy filter and {% crispy %} tag that will let you control the rendering behavior of your Django forms in a very elegant and DRY way.

Contributing

  • Django-Authentication is a simple project, so you can contribute to it by just adding your code to the project to improve it.
  • If you have any questions, please feel free to open an issue or create a pull request.

Download Details:
Author: yezz123
Source Code: https://github.com/yezz123/Django-Authentication
License: MIT License

#django #python