Blog#3 : SQL Statements

 

In this blog, we will be going through different types of SQL statements.

So let’s get started.

 

Types of SQL Commands.

 

SQL (Structured Query Language) is the database language that is used to interact with the database. As all the languages have some specific set of ground rules so does SQL.

Today we will be going through the basic types of SQL statements.

SQL statements are broadly classified into 5 categories.

1.      Data Definition Language (DDL)

2.      Data Manipulation Language (DML)

3.      Data Control Language (DCL)

4.      Transaction Control Language (TCL)

5.      Data Query Language (DQL)

 

 

Data Definition Language (DDL)

               Data Definition Language (DDL) is used to create and modify the structure of database objects in the database.  In simple, we can say that the DDL command is used to define your database or preparing the structure of the database.

Examples of DDL statements.

1.      Create: To Create a Database or its objects

2.      Drop: To delete the database or its objects

3.      Alter: To modify the database or its objects

4.      Truncate: To remove all the data from a table

 

Data Manipulation Language (DML)

               As the name suggests DML statements are used to manipulate the data in a Database / Schema. DML statements will not change any structure of the database but only the data in a table.

Examples of DML Statements.

1.      Insert: To insert the data into a table

2.      Update: To update the data in a table

3.      Delete: To delete the data in a table

Data Control Language (DCL)

 

               Data Control Language (DCL) deals with allowing and removing the rights and the permission to a user to access the database.

Examples of DCL commands:

1.      Grant: Gives user access privileges on the database

2.      Revoke: Remove/Withdraw user access privileges on the database

 

Transaction Control Language (TCL)

              

               Transaction Control Language (TCL) deals with the transaction happening in the database.

 

Examples for TCL commands:

1.      Commit: Marks are the transaction is completed.

2.      Rollback: Undo all the commands if any error occurs

3.      Savepoint: Sets a save point for a transactions

 

Data Query Language (DQL)

 

               Data Query Language (DQL) deals with the retrieval of the data from the table.

Example of DQL statement:

1.      Select: Used to retrieve the data from the database

So these were the basic types of commands used in SQL. However, the number of types might be different if you check on other websites.

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Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.