Executing DDL and DML Commands

Executing DDL and DML Commands

• SQL stands for Structured Query Language(SQL).
• It is the database language by the use of which we can perform certain operations on the existing database.
• We can use this language to create a database. 
• SQL uses certain commands like Create, Drop, Insert, etc. to carry out the required tasks.

These SQL commands are mainly categorized into four categories as:

• DDL – Data Definition Language
• DML – Data Manipulation Language
• DCL – Data Control Language
• TCL – Transaction Control Language

DDL: 

• DDL stands for Data Definition Language.
• DDL consists of the SQL commands that can be used to define the database schema. 
• It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in the database.
• Examples of DDL commands:
• CREATE – is used to create the database or its objects.
• DROP – is used to delete objects from the database.
• ALTER-is used to alter the structure of the database.
• TRUNCATE–is used to remove all records from a table.
• RENAME –is used to rename an object existing in the database.

DML: 

• DML stands for Data Manipulation Language.
• The SQL commands that deal with the manipulation of data present in the database.
• Examples of DML:
• INSERT – is used to insert data into a table.
• UPDATE – is used to update existing data within a table.
• DELETE – is used to delete records from a database table.
• SELECT – is used to retrieve data from the database.

DCL: 

• DCL stands for Data Control Language.
• DCL includes commands such as GRANT and REVOKE which mainly deals with the rights, permissions and other controls of the database system.
• Examples of DCL commands:
• GRANT-gives user’s access privileges to the database.
• REVOKE-withdraw user’s access privileges given by using the GRANT command.

TCL

• TCL stands for Transaction Control Language
• TCL commands deal with the transaction within the database.
• Examples of TCL commands:
• COMMIT– commits a Transaction.
• ROLLBACK– rollbacks a transaction in case of any error occurs.
• SAVEPOINT–sets a savepoint within a transaction.
• SET TRANSACTION–specify characteristics for the transaction.