🔹 Unit 1: Basics of Relational Model (आधारभूत बातें)

⭐ Very Repeated

1️⃣ Define Relation, Tuple, Attribute, Domain with example

• Relation (टेबल) → rows + columns ka collection

• Tuple (पंक्ति / Row) → ek record

• Attribute (कॉलम / गुण) → field/column

• Domain (मानों का समूह) → possible values ka set

👉 Example:

Relation = Student table
Tuple = (1, Mansi, 85)
Attribute = Name
Domain = Marks (0–100)

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2️⃣ What is Relational Model?

Relational Model ek database structure hai jisme data tables (सारणियों) me store hota hai.

Features (विशेषताएँ):

✔ Table format
✔ Easy queries
✔ Data integrity
✔ Less redundancy

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3️⃣ Explain Keys in DBMS (कुंजी)

Keys help to identify records uniquely (अद्वितीय पहचान)

Types:

• Primary Key (प्राथमिक कुंजी)

• Foreign Key (विदेशी कुंजी)

• Candidate Key (संभावित कुंजी)

• Super Key

• Composite Key (संयुक्त कुंजी)

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4️⃣ Difference

Primary Key vs Foreign Key

Super Key vs Candidate Key

• Super key → extra attributes ho sakte hain

• Candidate key → minimum attributes (न्यूनतम)

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5️⃣ Integrity Constraints (अखंडता नियम)

Rules jo data ko correct & valid (सही और मान्य) rakhte hain

Types:
✔ Domain constraint
✔ Key constraint
✔ Entity integrity
✔ Referential integrity

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🔹 Unit 2: Functional Dependency (FD) (कार्यात्मक निर्भरता)

6️⃣ Functional Dependency

A → B
A decide kare B ko

👉 Example:
Roll → Name

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7️⃣ Types

• Trivial FD (तुच्छ) → A → A

• Non-trivial FD (गैर-तुच्छ) → A → B

• Fully Functional Dependency → full key par depend

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8️⃣ Closure of attribute set (क्लोज़र निकालना)

A⁺ = all attributes jo A se mil sakte hain

Use:
✔ candidate key find karne ke liye

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9️⃣ Candidate Key using FD

Steps:

1. Closure nikalo

2. Sab attributes cover kare → key

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🔟 Armstrong’s Axioms (नियम)

Rules:
✔ Reflexivity
✔ Augmentation
✔ Transitivity

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1️⃣1️⃣ Minimal / Canonical Cover (न्यूनतम आवरण)

FD set ko simplest form (सरल रूप) me convert karna

Steps:
✔ Extra attributes remove
✔ Duplicate remove
✔ Combine

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🔹 Unit 3: Normalization (सामान्यीकरण) 🔥 Most Important

1️⃣2️⃣ What is Normalization?

Process to remove redundancy (दोहराव हटाना) and avoid anomalies (त्रुटियाँ रोकना)

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Normal Forms

1NF (प्रथम सामान्य रूप)

✔ No repeating groups
✔ Atomic values (एकल मान)

2NF (द्वितीय सामान्य रूप)

✔ 1NF
✔ No Partial Dependency (आंशिक निर्भरता नहीं)

3NF (तृतीय सामान्य रूप)

✔ 2NF
✔ No Transitive Dependency (संक्रमण निर्भरता नहीं)

BCNF

✔ Strong form of 3NF
✔ Every determinant is candidate key

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Differences

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Important Terms

• Partial Dependency (आंशिक निर्भरता)

• Transitive Dependency (संक्रमण निर्भरता)

• Anomalies (Insertion/Deletion/Update समस्याएँ)

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Questions Practice

✔ Normalize table into 3NF
✔ Normalize into BCNF
✔ Check lossless join

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Lossless Join Decomposition (हानिरहित संयोजन)

Data loss na ho after split

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Dependency Preservation (निर्भरता संरक्षण)

All FD remain valid after decomposition

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🔹 Unit 4: Decomposition (विभाजन)

Decomposition

Big table ko small tables me todna

Types:
✔ Lossless (सही)
✔ Lossy (गलत)

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Algorithms

✔ 3NF decomposition steps
✔ BCNF decomposition steps

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🔹 Unit 5: ER to Relational Mapping (ईआर से टेबल बनाना)

✔ ER Diagram → Tables
✔ One-One
✔ One-Many
✔ Many-Many
✔ Weak entity (कमजोर इकाई)
✔ Multivalued attribute
✔ Specialization/Generalization

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📌 Long Answer Questions (5–10 Marks)

Prepare:
✔ Normalize step by step
✔ Candidate key find
✔ Minimal cover
✔ BCNF decomposition
✔ Design database for:

• Library (पुस्तकालय)

• Student (छात्र)

• Banking (बैंक)

• Hospital (अस्पताल)

• Railway (रेलवे आरक्षण)

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📌 Short Notes (2–3 Marks)

Prepare definitions:
✔ Super key
✔ Candidate key
✔ Composite key
✔ Surrogate key
✔ FD
✔ Normalization
✔ Anomaly
✔ Lossless join
✔ Dependency preservation