DBMS mein topics bohot hain magar exam mein aate kuch specific hi hain. Sahi topics pe focus karo toh good marks pakke hain.
Strategy: Theory + SQL dono aate hain — dono equally prepare karo.
1 ER Diagram — Sabse Common Question
ER Diagram har saal exam mein aata hai 🗄️
- Entity, Attribute, Relationship — teen cheezein clearly samjho
- Strong vs Weak Entity ka difference
- 1:1, 1:N, M:N relationships draw karna
- Simple, Composite, Multivalued, Derived Attributes
- Practice: Library Management ya College System ka ER banana
2 Normalization
- 1NF: Atomic values — koi repeating groups nahi
- 2NF: 1NF + No partial dependency
- 3NF: 2NF + No transitive dependency
- BCNF: 3NF ka stricter version
Trick: Ek table leke 1NF se BCNF tak step-by-step apply karo — yahi exam mein aata hai.
3 SQL — Ye Aana Hi Chahiye
SQL queries practice se pakki hoti hain 💾
- SELECT, WHERE, ORDER BY, GROUP BY, HAVING
- JOIN types — INNER, LEFT, RIGHT
- Aggregate functions — COUNT, SUM, AVG, MAX, MIN
- Subqueries, CREATE/INSERT/UPDATE/DELETE
- Constraints — PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL
4 ACID Properties
- Atomicity: Transaction poora hoga ya bilkul nahi
- Consistency: Database valid state mein rahega
- Isolation: Concurrent transactions ek doosre ko affect nahi karenge
- Durability: Committed transaction permanent rahega
5 Concurrency Control
- Problems: Lost Update, Dirty Read, Unrepeatable Read
- Two-Phase Locking (2PL) Protocol
- Deadlock — definition, detection, prevention
Summary: ER Diagram + Normalization + SQL = 70% marks. Transactions + Concurrency = baaki 30%. Smart study!
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