장 성훈

장 성훈

1611721980

제품판매웹앱 구현 - 07.DB 테이블 설계하기

제품판매웹앱 구현 - 07.DB 테이블 설계하기

#database

What is GEEK

Buddha Community

제품판매웹앱 구현 - 07.DB 테이블 설계하기
장 성훈

장 성훈

1611721980

제품판매웹앱 구현 - 07.DB 테이블 설계하기

제품판매웹앱 구현 - 07.DB 테이블 설계하기

#database

Ikram Mihan

Ikram Mihan

1582683309

An Overview of Azure Cosmos DB

In this article, we will discuss Azure Cosmos DB. We will answer questions such as: What is a Cosmos DB? Why do we need to use the Cosmos DB? We will also learn how to create a new Azure Cosmos DB account using Azure subscriptions, how to create a new database and collection using Azure, and how to add data to the collection.

In this article, we will see the following,

  • What is Azure Cosmos DB?
  • Why do we need to use the Cosmos DB?
  • How to create a new Azure Cosmos DB account using Azure
  • How to create a new database and collection using Azure
  • How to add data to the collection using Data Explorer
  • How to use SQL Query to the collection using Data Explorer
  • How to get Cosmos DB connection string from Azure

Prerequisite

  • Azure Subscriptions

What is Azure Cosmos DB?

Azure Cosmos DB is a globally distributed database service. It supports multi-model approaches such as the document, Key/Value, wide columns and graph databases using APIs.

The list of APIs such as the following:

  • SQL API
  • MongoDB API
  • Graph API
  • Table API
  • Cassandra API

Why do we need to use the Cosmos DB?

Azure Cosmos DB is offering the following items:

  • Global distributions
  • Elastic scale out
  • Guaranteed low latency
  • Five consistency models
  • Comprehensive SLAs

How to create a new Azure Cosmos DB account using Azure

You can learn in this section, how to create a new Azure cosmos database account using the Azure portal with the following guidelines.

Go to open the new browser, you can copy and paste the following URL

https://portal.azure.com/

Then, sign in to the Azure portal using Microsoft Account credentials:

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After successfully logging into the Azure portal, you can see the dashboard looks like the following screenshot.

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You can go to create a resource-Databases - click the Azure Cosmos DB.

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The Azure Cosmos DB new account window will be opened and you can enter the following details, which are required. Then, click the Create button.

ID
API
Subscription Name
Resource Group Name
Location

The list of API options is available in the following screenshot:

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Now, you can see the notification window displaying the deployment in progress notification. Once it is completed you will get the deployment succeeded notification in the notification window. Then, click the go to resource button.

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After successfully creating the Azure Cosmos DB account, the Congratulations! Your Azure Cosmos DB account was created window will be opened, as in the following screenshot.

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How to create a new database and collection using Azure

You will learn in this section, how to create a new database and collection in Data Explorer using Azure portal.

You can go to Data Explorer - click the New Collections

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The Add Collection window will be opened and you can enter the following details, which are required. Then, click the OK button.

  • Database Id
  • Collection Id
  • Storage Capacity
  • Throughput

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You can see the new database and collection looks at the following screenshot.

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How to add data to the collection using Data Explorer

You can learn in this section, how to add sample data to the collection in Data Explorer using Azure portal at the following guidelines.

You can go to Data Explorer - Expand the Table collection in the Collection window, click the Documents - click the New Document.

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The new document window will be opened and add the data to the collection with the following format.

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{  
   “Id”: “1”,  
   “TableName”: “Table A”,  
   “Location”: “Front Row”,  
   “Status”: “Available”,  
   “Date”: “28-02-2018”  
}  

Once you have added json data to the document, click the Save button.

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After successfully added records to the collection it looks like the following screenshot:

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How to add SQL Query to the collection using Data Explorer

You can learn in this section, how to use SQL query to the collection in Data Explorer using Azure portal at the following guidelines.

You can go to Data Explorer - Expand the Table collection in the Collection window, click the New SQL Query

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The Query window will be opened as in the below screenshot

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Once you have executed query by clicking Execute Query button:

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You can use the Where condition and Order By for the select statement on SQL Query window in the Azure Cosmos DB as in the below screenshots:

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How to get Cosmos DB connection string from Azure

You will learn in this section, how to get the Cosmos DB connection string in Keys using the Azure portal.

You can go to Settings - click the Keys

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Now you can copy the URI and Primary Key into your web.config file in your project

Conclusion

I hope you understand now about Azure Cosmos DB, how to create a new Azure Cosmos DB account using Azure, how to create a new database and collection using Azure, how to add data to the collection using Data Explorer, how to use SQL Query to the collection using Data Explorer and how to get Cosmos DB connection string from Azure. I have covered all the required things. If you find anything missing, please let me know. Thank you!

#Azure #Azure Cosmos DB #Cosmos DB

Cody  Osinski

Cody Osinski

1624469280

Understanding how to query arrays in Azure Cosmos DB

This blog is the final part of a series of blogs where we’ll demystify commonly confused concepts for developers learning how to query data using the SQL (core) API in Azure Cosmos DB. Today, we’ll walk through tips and tricks for querying arrays.

Using an example, we’ll show how to use these concepts when querying arrays:

  • Accessing a specific array element
  • Iterating over arrays
  • JOINs
  • Subqueries

Example Scenario:

Nick is a developer that created an app that stores shopping lists. His app is incredibly popular around the holidays and has soared to 1 million active users!

He has a Cosmos container that has the shopping lists modeled as JSON documents. Here’s an example document:

{
  "id": "Tim",
  "city": "Seattle",
  "gifts": [
     {
        "recipient": "Andrew",
        "gift": "blanket"
     },
     {
        "recipient": "Deborah",
        "gift": "board game"
     },
     {
        "recipient": "Chris",
        "gift": "coffee maker"
     }
  ]
}

The remainder of the blog will focus on ways to query arrays, starting with the simplest (and least expressive) and concluding with the more advanced concepts.

#core (sql) api #query #azure cosmos db #azure #cosmos db

Eric  Bukenya

Eric Bukenya

1624713540

Learn NoSQL in Azure: Diving Deeper into Azure Cosmos DB

This article is a part of the series – Learn NoSQL in Azure where we explore Azure Cosmos DB as a part of the non-relational database system used widely for a variety of applications. Azure Cosmos DB is a part of Microsoft’s serverless databases on Azure which is highly scalable and distributed across all locations that run on Azure. It is offered as a platform as a service (PAAS) from Azure and you can develop databases that have a very high throughput and very low latency. Using Azure Cosmos DB, customers can replicate their data across multiple locations across the globe and also across multiple locations within the same region. This makes Cosmos DB a highly available database service with almost 99.999% availability for reads and writes for multi-region modes and almost 99.99% availability for single-region modes.

In this article, we will focus more on how Azure Cosmos DB works behind the scenes and how can you get started with it using the Azure Portal. We will also explore how Cosmos DB is priced and understand the pricing model in detail.

How Azure Cosmos DB works

As already mentioned, Azure Cosmos DB is a multi-modal NoSQL database service that is geographically distributed across multiple Azure locations. This helps customers to deploy the databases across multiple locations around the globe. This is beneficial as it helps to reduce the read latency when the users use the application.

As you can see in the figure above, Azure Cosmos DB is distributed across the globe. Let’s suppose you have a web application that is hosted in India. In that case, the NoSQL database in India will be considered as the master database for writes and all the other databases can be considered as a read replicas. Whenever new data is generated, it is written to the database in India first and then it is synchronized with the other databases.

Consistency Levels

While maintaining data over multiple regions, the most common challenge is the latency as when the data is made available to the other databases. For example, when data is written to the database in India, users from India will be able to see that data sooner than users from the US. This is due to the latency in synchronization between the two regions. In order to overcome this, there are a few modes that customers can choose from and define how often or how soon they want their data to be made available in the other regions. Azure Cosmos DB offers five levels of consistency which are as follows:

  • Strong
  • Bounded staleness
  • Session
  • Consistent prefix
  • Eventual

In most common NoSQL databases, there are only two levels – Strong and EventualStrong being the most consistent level while Eventual is the least. However, as we move from Strong to Eventual, consistency decreases but availability and throughput increase. This is a trade-off that customers need to decide based on the criticality of their applications. If you want to read in more detail about the consistency levels, the official guide from Microsoft is the easiest to understand. You can refer to it here.

Azure Cosmos DB Pricing Model

Now that we have some idea about working with the NoSQL database – Azure Cosmos DB on Azure, let us try to understand how the database is priced. In order to work with any cloud-based services, it is essential that you have a sound knowledge of how the services are charged, otherwise, you might end up paying something much higher than your expectations.

If you browse to the pricing page of Azure Cosmos DB, you can see that there are two modes in which the database services are billed.

  • Database Operations – Whenever you execute or run queries against your NoSQL database, there are some resources being used. Azure terms these usages in terms of Request Units or RU. The amount of RU consumed per second is aggregated and billed
  • Consumed Storage – As you start storing data in your database, it will take up some space in order to store that data. This storage is billed per the standard SSD-based storage across any Azure locations globally

Let’s learn about this in more detail.

#azure #azure cosmos db #nosql #azure #nosql in azure #azure cosmos db

Juana  O'Keefe

Juana O'Keefe

1599003000

View SQLite DB in Flutter Application

In this small article, I’ll show you how you can see the data in SQLite DB of your flutter application. In the previous two articles, we’ve covered SQLite CRUD Operation in Flutter App.

Credit to Stack Overflow answer here.

Where is Databases are stored ?

When you create an SQLite DB programmically, did you thought about physically location of the DB? If you are coming from web development, you might look into project explorer for a file with the extension ‘db’. But it’s not in the project directory.

It depends on the environment – android or IOS. To find the location of the database we’ve used a package  path_provider in previous article. The db will be stored somewhere in the emulator. To see the path I’ve added the  print statement in  _initDatabase method of  DatabaseHelper class.

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_initDatabase() async {
    ...
    String dbPath = join(dataDirectory.path, _databaseName);
    print('db location : '+dbPath);
    ...
  }

Now to see the printed output, If you are on VS Code, open  Debug Console ( from view menu ). In my case it prints as follows.

View SQLite DB physical location

#flutter #flutter article #how to query sqlite db in flutter #view database in flutter app #view sqlite db in flutter app