SQL language DDL DML DCL tcl four languages

1.DDL (data definition Language) database definition language: DDL gives us the ability to create or delete tables. You can define indexes (keys), specify links between tables, and impose constraints between tables.

? Common DDL Statements:

–create database (creating new databases)

–alter database (modifying databases)

–create table (Create new table)

–alter Table (change (change) database table)

–drop table (deleting tables)

–create index (search key)

–drop Index (delete index)

2? DML (data manipulation Language) Manipulation language: Provided by the DBMS for use by the user or programmer,

Implement operations on data in the database.

? Common DML Statements:

–select (fetching data from a database table)

–update (updating data in a database table)

–delete (deleting data from a database table)

–insert into (inserting data into a database table)

.3.DCL (Data Control Language) database Control Language Authorization, role control, etc.

–grant (Authorized)

–revoke (Cancellation of Authorization)

? 4. TCL (Transaction control Language) transaction Control Language

–savepoint (set save point)

–rollback (rollback)

–commit (Commit data (from memory update to physical file))

SQL language DDL DML DCL tcl four languages