DML(Data Manipulation Language)

Yeh SQL ka ek part hai jo database ke data ko insert, update, delete, aur retrieve (yaani fetch) karne ke liye use hota hai.

DML commands ka use hum table ke andar ke data par kaam karne ke liye karte hain.

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 DML ke Important Commands

 Example Table: Students 

Maan lo humare paas ek table hai:

 1. SELECT – Data ko dekhna

SELECT command ka use table se data dekhne/fetch karne ke liye hota hai.

 Syntax:

 Example:

 Output:

 2. INSERT – Naya data add karna

Is command ka use table mein naya row add karne ke liye hota hai.

 Syntax:

 Example:

 Table after INSERT:

 3. UPDATE – Existing data ko change karna

UPDATE command ka use kisi row ke value ko modify/update karne ke liye hota hai.

 Syntax:

 Example:

 Table after UPDATE:

 4. DELETE – Data ko delete karna

DELETE command ka use kisi row ko table se delete karne ke liye hota hai.

 Syntax:

 Example:

 Table after DELETE:

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 Dhyan dene wali baatein:

• -> UPDATE aur DELETE mein hamesha WHERE lagana chahiye, warna poora table ka data change ya delete ho sakta hai.

• -> DML sirf data par kaam karta hai, table structure par nahi (table banane ke liye DDL use hota hai).

• -> Agar DBMS transaction support karta ho, to DML changes ko ROLLBACK bhi kiya ja sakta hai.

 Real-Life Example:

Socho ek class register (attendance sheet) hai:

• INSERT – Naye student ka naam jodna

• SELECT – Kisi student ka record dekhna

• UPDATE – Galat age correct karna

• DELETE – Student ka naam hata dena (agar woh chala gaya ho)