What is an SQI code?

SQL stands for Structured Query Language. It is a set of commands to interact with data on database - including removing, editing and adding data.

SQL stands for Structured Query Language - It acts as an interface between the user and the actual database (e.g. Oracle, SQL Server, MySQL). SQL includes SQL commands.

SQL Commands are classified into 4 groups

1. DDL - Data Definition Language

 - These commands deal with META-DATA or structure of table

List of commands in DDL:

CREATE - Used to create a table, user, database etc

ALTER - Used to alter table structure (e.g. add new column, update an existing column

DROP - Used to drop table or user or database

2. DML - Data Manipulation Language

 - This language commands are used to deal with the actual table data

 -> These commands Deals with Rows

 -> These commands are used to perform CRUD operations

 C - Create record using "INSERT" command

 R - Read tables data using "SELECT" command

 U - Update records using "UPDATE" command

 D - Delete records using "DELETE" command

3. DCL - Data Control Language

 - This language commands are used to control data access

 - These commands are used by database administrators

 List of commands

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 GRANT - to grant permissions to the users

 REVOKE - To revoke permissions from the users

4.TCL - Transaction Control Language

 - These commands are used to manage database transactions

 List of commands

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  COMMIT

  ROLLBACK