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    •  Assertions in DBMS 

     Assertion kya hota hai?

    DBMS (Database Management System) mein Assertion ek condition ya rule hota hai jo hamesha true (sahi) rehna chahiye database ke data ke liye.
    Ye automatic check karta hai ki database mein galat ya rule ke khilaaf data na jaaye.

     Socho jaise ek rule-setting alarm hai – agar koi galti se rule todta hai, to system turant uss action ko reject kar deta hai.

     Assertions ki zarurat kyun padti hai?

    • Ye data ko correct aur consistent banaye rakhte hain.

    • Galat data ko database mein enter hone se rok dete hain.

    • Ye business rules ko database ke level pe enforce karte hain.

     Example Samajho:

     Students Table:

    StudentID Name Department TotalCredits
    101 Aditi CSE 120
    102 Rahul ECE 70

     Rule:

    University ka rule hai ki koi bhi student graduate nahi ho sakta jab tak uske paas kam se kam 100 credits na ho.

    Is rule ko hum Assertion ke through enforce kar sakte hain.

     SQL mein Assertion Create karne ka syntax

    Syntax: 
    CREATE ASSERTION assertion_name
    CHECK ( condition );

    Hamare example main:

    CREATE ASSERTION CreditCheck
    CHECK (
    NOT EXISTS (
    SELECT * FROM Students
    WHERE TotalCredits < 100
    )
    );

     Iska matlab:

    • Ye check karta hai ki Students table mein kisi bhi student ke credits 100 se kam na ho.

    • Agar koi student <100 credits ke saath add/update hota hai, to DBMS uss operation ko reject kar dega.

     Assertion ke Important Points

    Feature Description
    Scope Assertion poore database pe apply hota hai
    Power Ye multiple rows/tables ke data pe rule laga sakta hai
    Use Complex business rules ko enforce karne ke liye
    Example “Har student ke paas ≥ 100 credits hone chahiye”
    Support Har DBMS mein support nahi hota (e.g. MySQL mein nahi, PostgreSQL mein hota hai)

     Assertions ke Limitations 

    • Har DBMS mein support nahi hota (e.g., MySQL X)

    • Complex rule hone par performance slow ho sakti hai

    • Debugging mushkil ho sakta hai agar assertion bada ho

     Alternatives agar Assertion support nahi kare:

    Agar aapka DBMS CREATE ASSERTION support nahi karta, to aap ye options use kar sakte ho:

    • Triggers banayein (action ke pehle ya baad check karne ke liye)

    • Check Constraints (agar single row ya table ke liye rule hai)

    • Stored Procedures ke through manual checks lagayein

     Summary:

    • -> Assertions aise rules hote hain jo database mein hamesha true rehne chahiye

    • -> Ye rules poore database pe apply hote hain

    • -> Assertions se invalid data enter nahi ho sakta

    • -> Helpful in enforcing important business logic

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