DDL vs DML Commands

SQL commands ko unke kaam ke basis par categories me baanta gaya hai. Do sabse important categories hain DDL aur DML.

DDL (Data Definition Language)

Yeh commands database ke structure (schema) ko define karne ya badalne ke kaam aati hain. Inke chalte hi changes auto-commit (permanently save) ho jaate hain.

• CREATE: Naya database, table, ya view banana.
• ALTER: Maujooda table ke structure ko badalna (e.g., naya column add karna).
• DROP: Poore table ko uske structure ke saath delete karna.
• TRUNCATE: Table ke andar ka saara data ek saath delete karna (structure bana rehta hai).
• RENAME: Ek object ka naam badalna.

DML (Data Manipulation Language)

Yeh commands table ke andar ke data par kaam karne (manipulate karne) ke liye hoti hain. Inko COMMIT ya ROLLBACK kiya jaa sakta hai.

• SELECT: Data ko retrieve (dekhna).
• INSERT: Table me nayi rows (records) daalna.
• UPDATE: Maujooda rows ko modify karna.
• DELETE: Rows ko delete karna.

Iske alawa DCL (Data Control Language) - GRANT, REVOKE aur TCL (Transaction Control Language) - COMMIT, ROLLBACK, SAVEPOINT bhi hote hain.