Different types of SQL Commands

SQL Commands are divided into five broad categories – DDL, DML, DCL, TCL, and DQL. Each category is further explained below:

1) DDL- Data Definition Language?

The Data Definition Language is made up of SQL commands that can be used to design the database structure. It simply handles database schema descriptions and is used to construct and modify the structure of database objects in the database.

It can be used to define the database schema. It allows adding/modifying/deleting the logical structures which contain the data or which would enable users to access/maintain the data

○CREATE - to create a database and its objects

○ALTER - alters the structure of the existing databases

○DROP - delete objects from the databases

○TRUNCATE - remove all records from a table, including memory allocated for the records are removed

2) DQL- Data Query Language?

DQL statements are used to query the data contained in schema objects. The DQL Commands' goal is to return a schema relation depending on the query supplied to it. DQL can be defined as follows: It’s a part of a SQL statement that lets you get data from a database and put it in order.

The most used code by Data scientists and analysts.

1. SELECT: It helps to do data analysis

3) DML- Data Manipulation Language?

The SQL commands that deal with manipulating data in a database are classified as DML (Data Manipulation Language), which covers the majority of SQL statements. It’s the part of the SQL statement that regulates who has access to the data and the database

It helps us work with data that goes into the database?such as

○SELECT - Retrieves data from a Table/Database

○INSERT - Insert data into a Table/Database

○UPDATE - Updates existing data within a Table/Database

○DELETE - Deletes all records from a database Table/Database

4) DCL- Data Control Language?

DCL (Data Controlling Language) is a query language that allows users to retrieve and edit data held in databases. The types of Data Controlling Language commands include Grant and Revoke.

It allows us to give permission on a particular database or table such as GRANT & REVOKE

●GRANT – Allows users to access privileges to the database/table

●REVOKE - withdraw users' access privileges given by using the GRANT command

5) TCL- Transaction Control Language?

Transaction Control Language (TCL) instructions are used in the database to manage transactions. This command is used to handle the DML statements’ modifications. TCL allows you to combine your statements into logical transactions.

It helps to commit and revoke changes in the server. Also, it allows us to save points wherever it is appropriate.

●COMMIT– Saves all the changes done in the last transaction permanently.

●ROLLBACK - Cancels all the modifications done in the last transaction.

SAVEPOINTS - A rollback operation will be performed on a part of the transaction. The save points command sets a name transaction save-point by the name of the identifier

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