📘 DBMS & Software Engineering – One-Page Revision Guide
Perfect for GATE | UGC NET | BPSC | KVS | NVS | EMRS | University Exams
📚 PART 1: DBMS – One Page Revision Sheet
1️⃣ Database Basics
Database → Organized collection of data
DBMS → Software to store, retrieve & manage data
Advantages:
Data sharing
Security
Consistency
Integrity
Backup & recovery
2️⃣ Data Models
Hierarchical → Tree structure
Network → Graph structure
Relational → Tables (Rows = Tuples, Columns = Attributes) ⭐
ER Model → Entity, Attribute, Relationship
3️⃣ Keys (⭐ Very Important)
Super Key → Uniquely identifies a tuple
Candidate Key → Minimal super key
Primary Key → Chosen candidate key
Alternate Key → Candidate key not chosen
Foreign Key → References PK of another table
Composite Key → Multiple attributes
4️⃣ Normalization (Most Repeated)
| Normal Form | Removes |
|---|---|
| 1NF | Repeating groups, multivalued attributes |
| 2NF | Partial dependency |
| 3NF ⭐ | Transitive dependency |
| BCNF | Non-superkey determinants |
| 4NF | Multivalued dependency |
| 5NF | Join dependency |
🔑 Exam Trick:
Partial dependency → 2NF
Transitive dependency → 3NF
5️⃣ Functional Dependency
X → Y : X determines Y
Full FD → Depends on whole key
Partial FD → Depends on part of key
Transitive FD → Depends on non-key attribute
6️⃣ SQL Commands
DDL: CREATE, ALTER, DROP, TRUNCATE
DML: SELECT, INSERT, UPDATE, DELETE
DCL: GRANT, REVOKE
TCL: COMMIT, ROLLBACK, SAVEPOINT
7️⃣ Joins
INNER JOIN → Matching records
LEFT JOIN → All left + matched right
RIGHT JOIN → All right + matched left
FULL JOIN → All records
CROSS JOIN → Cartesian product
8️⃣ Transactions (ACID)
A → Atomicity
C → Consistency
I → Isolation
D → Durability
9️⃣ Concurrency Control
Problems: Lost update, Dirty read, Unrepeatable read
Techniques: Locking, Timestamp ordering
Deadlock: Circular wait
Solutions: Prevention, Detection, Avoidance
🔟 Indexing
Primary Index → On primary key
Secondary Index → On non-key attribute
Clustered Index → Physical order
Non-clustered Index → Logical order
🔥 Frequently Asked PYQ Facts
Transitive dependency → 3NF
Best normalization balance → 3NF
Highest data integrity → BCNF
SQL Injection → Security attack
Hadoop is written in → Java
⚡ Last-Minute DBMS Exam Tricks
More normalization → Less redundancy
More joins → More processing cost
Index speeds up SELECT, slows INSERT
TRUNCATE ≠ DELETE (No rollback)
💻 PART 2: Software Engineering – One Page Revision Sheet
1️⃣ Software Basics
Software = Programs + Documentation + Configuration data
Software Engineering = Systematic & disciplined approach to software development
2️⃣ Software Process Models
| Model | Key Point | Use |
|---|---|---|
| Waterfall | Linear | Stable requirements |
| Incremental | Build in parts | Early delivery |
| Spiral | Risk-driven | Large, high-risk projects |
| Agile | Iterative | Dynamic requirements |
| V-Model | V&V | Safety-critical systems |
📌 Most exams focus on: Waterfall & Spiral
3️⃣ SDLC Phases (Very Important)
Requirement → Design → Implementation → Testing → Deployment → Maintenance
🧠 Mnemonic: R-D-I-T-D-M
4️⃣ Cohesion (Internal Strength)
Best → Worst:
Functional ⭐ > Sequential > Communicational > Procedural > Temporal > Logical > Coincidental
5️⃣ Coupling (Inter-module Dependency)
Worst → Best:
Content ❌ > Common > Control > Stamp > Data ⭐
✔️ Good Design Rule: High Cohesion + Low Coupling
6️⃣ Software Metrics
LOC → Size based
Function Point (FP) → Functionality based
Cyclomatic Complexity → Logical complexity
Formula: V(G) = E − N + 2P
7️⃣ Software Testing
Levels: Unit → Integration → System → Acceptance
Types:
Black Box → Functional testing
White Box → Path testing
Regression → Old features
Alpha → Developer site
Beta → User site
8️⃣ Verification vs Validation
| Verification | Validation |
|---|---|
| Building it right? | Building right product? |
| No execution | Execution required |
9️⃣ CASE Tools
Upper CASE → Requirement & Design
Lower CASE → Coding & Testing
Integrated CASE → Full SDLC
🔟 Software Maintenance
| Type | Meaning |
|---|---|
| Corrective | Bug fixing |
| Adaptive | Environment change |
| Perfective | Performance improvement |
| Preventive | Future fault prevention |
📌 Maintenance takes ~70% cost
🔑 Most Repeated Exam Facts
Best Cohesion → Functional
Best Coupling → Data
Worst Coupling → Content
Maintenance takes maximum effort
Agile focuses on customer satisfaction
🏆 One-Line Golden Rule
Good Software = High Cohesion + Low Coupling + Proper Testing
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