Query relational data in Azure

28 Sep 2021

Introduction to SQL

• SQL -> Structured Query Language
• Used to communicate with a relational database
• update data in a database, or retrieve data from a database
• SQL include Microsoft SQL Server, MySQL, PostgreSQL, MariaDB, and Oracle.
• SELECT, INSERT, UPDATE, DELETE, CREATE, and DROP
• Security management and programmability
• Microsoft SQL Server -> uses Transact-SQL -> writing stored procedures and triggers and managing user accounts
• Popular dialects of SQL include:
  • Transact-SQL (T-SQL) -> Microsoft SQL Server and Azure SQL Database.
  • pgSQL -> PostgreSQL.
  • PL/SQL -> Oracle -> Procedural Language/SQL.

SQL statement types

• SQL statements are grouped into two main logical groups, and they are:
• Data Manipulation Language (DML)

Statement	Description	Applied
SELECT	Select/Read rows from a table	By Default, Every Row at a time
INSERT	Insert new rows into a table	One Row at a time
UPDATE	Edit/Update existing rows	By Default, Every Row at a time
DELETE	Delete existing rows in a table	By Default, Every Row at a time
DROP	all the rows in that table are lost.	By Default, Every Row at a time

#### Data Types : 1) INT 2) VARCHAR 3) NOT NULL

• Data Definition Language (DDL)

Retrieve connection information for Azure SQL Database

Tools to query data held in Azure SQL Database:

• The query editor in the Azure portal
• The sqlcmd utility from the command line or the Azure Cloud Shell
• SQL Server Management Studio
• Azure Data Studio
• SQL Server Data Tools

Find the details about using the tools

Retrieve connection information for Azure Database for PostgreSQL

• psql psql utility is available in the Azure Cloud Shell -> to query a database

Retrieve connection information for Azure Database for MySql

• Use MySql Benchmark.

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