Transactions in DBMS in Hindi + English

Transactions in DBMS

Transaction kya hota hai?

Transaction ka matlab hai ek group of operations (jaise read, write, update, delete) jo database par ek saath perform ki jaati hain. Ye operations ek single unit ki tarah treat kiye jaate hain.

Example: ₹1000 ko Account A se Account B me transfer karna
Isme ye steps honge:
Account A ka balance read karo
₹1000 minus karo
New balance write karo
Account B ka balance read karo
₹1000 add karo
New balance write karo

Yeh poora process ek hi transaction kehlaata hai. Agar beech mein koi step fail ho gaya, toh poora ka poora transaction cancel ho jaata hai — yeh rollback kehlata hai.

ACID Properties – Transaction ke rules

Transaction ko reliable banane ke liye, 4 important properties hoti hain – ACID:

Property	Meaning in Hinglish
A – Atomicity	Ya toh sab kuch hoga ya kuch bhi nahi hoga.
C – Consistency	Database hamesha valid state mein rehna chahiye.
I – Isolation	Ek transaction doosre se alag hona chahiye.
D – Durability	Transaction complete hone ke baad data permanent save ho jaata hai. Crash ke baad bhi change rehta hai.

Transaction ke States (Stages)

Transaction kuch stages se guzarta hai:

       Start
         ↓
      [Active]
         ↓
 [Partially Committed]
   ↓             ↓
[Committed]    [Failed]
   ↓             ↓
        End          [Rollback]
                 ↓
                                 End

Active: Transaction execute horha hai.
Partially Committed: Saare operations ho chuke hai, save hone ke liye ready hai.
Committed: Changes Database me permanently save ho chuke hai.
Failed: Something went wrong.
Aborted: Saare changes ko roll back kiya gaya.

Commit aur Rollback kya hota hai?

Command	Kya karta hai?
COMMIT	Changes ko permanently database mein save karta hai.
ROLLBACK	Changes ko undo karta hai, yaani pehle wali state mein le jaata hai.

Example:

BEGIN;
UPDATE account SET balance = balance - 1000 WHERE acc_id = 'A';
UPDATE account SET balance = balance + 1000 WHERE acc_id = 'B';
COMMIT;

Agar beech mein error aa gaya:

ROLLBACK;

Diagram se samjho

Successful Transaction Flow

[Start Transaction]
        ↓
[Read A] → [Update A] → [Write A]
        ↓
[Read B] → [Update B] → [Write B]
        ↓
     [Commit]

Error ke saath Transaction

[Start Transaction]
        ↓
[Read A] → [Update A] → [Write A]
        ↓
[Read B]
   ↓
 [Error!]
   ↓
 [Rollback all changes]

Transactions important kyun hote hain?

Data sahi rehta hai (Accuracy)
Banking system mein agar ₹1000 cut ho gaya lekin doosre account mein add nahi hua, toh dikkat ho sakti hai.
System crash hone par bhi safe
Rollback se hum data loss se bach sakte hain.
Multiple users ka safe access
Isolation ke through users apna kaam safe kar sakte hain bina clash ke.

Summary

Transaction ek group of steps hota hai jo database pe ek saath perform hote hain.
ACID properties se transaction reliable banta hai.
Commit = Save
Rollback = Undo
Real-life examples: Banking, shopping, ticket booking, etc.

The Hingineer

The Hingineer

DBMS

DBMS Part-1

DBMS Part-2

DBMS Part-3

DBMS Part-4

DBMS Part-5