SQL is a database computer language designed for the retrieval and management of data in relational database. SQL stands for Structured Query Language.
SQL
- Allows users to access data in relational database management systems.
- Allows users to describe the data.
- Allows users to define the data in database and manipulate that data.
- Allows to embed within other languages using SQL modules, libraries & pre-compilers.
- Allows users to create and drop databases and tables.
- Allows users to create view, stored procedure, functions in a database.
- Allows users to set permissions on tables, procedures, and views
SQL Commands:
The standard SQL commands to interact with relational databases are CREATE, SELECT, INSERT, UPDATE, DELETE and DROP. These commands can be classified into groups based on their nature:
DDL – Data Definition Language:
| Command | Description |
|---|---|
| CREATE | Creates a new table, a view of a table, or other object in database |
| ALTER | Modifies an existing database object, such as a table. |
| DROP | Deletes an entire table, a view of a table or other object in the database. |
DML – Data Manipulation Language:
| Command | Description |
|---|---|
| SELECT | Retrieves certain records from one or more tables |
| INSERT | Creates a record |
| UPDATE | Modifies records |
| DELETE | Deletes records |
DCL – Data Control Language:
| Command | Description |
|---|---|
| GRANT | Gives a privilege to user |
| REVOKE | Takes back privileges granted from user |