- 22 Jan, 2024
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Types of SQL Commands.
In the realm of relational databases, SQL (Structured Query Language) serves as the fundamental tool for interacting with and managing data. SQL commands are broadly categorized into Data Definition Language (DDL), Data Manipulation Language (DML), Data Control Language (DCL), Transaction Control Language (TCL), and Data Query Language (DQL), each serving distinct purposes.
1. Data Definition Language (DDL)
- CREATE: Used to create database objects like tables, views, or indexes.
- ALTER: Modifies the structure of existing database objects.
- DROP: Deletes database objects, such as tables or views.
- TRUNCATE: Removes all records from a table but retains the table structure.
2. Data Manipulation Language (DML)
- SELECT: Retrieves data from one or more tables.
- INSERT: Adds new records into a table.
- UPDATE: Modifies existing records in a table.
- DELETE: Removes records from a table.
3. Data Control Language (DCL)
- GRANT: Provides specific privileges to database users.
- REVOKE: Withdraws previously granted privileges.
4. Transaction Control Language (TCL)
- COMMIT: Finalizes a transaction, making all changes permanent.
- ROLLBACK: Reverts the database to its state before the beginning of a transaction.
- SAVEPOINT: Sets points within transactions to which you can later roll back.
5. Data Query Language (DQL)
- SELECT: Primarily used for querying the database to retrieve specific information.
Understanding and mastering these SQL command categories are essential for effective database management and manipulation. DDL commands shape the database structure, DML commands handle data modification, DCL commands manage access and permissions, TCL commands ensure transaction integrity, and DQL commands facilitate data retrieval. Whether you’re a database administrator, developer, or analyst, proficiency in these SQL command types is crucial for efficient and accurate data management.