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docs: add DBMS chapter 4 - normalization and chapter 5 - transactions #40

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146 changes: 146 additions & 0 deletions app/sem4/dbms/content/chapter4.tsx
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export const Ch4Content = () => {
return (
<div className="course-content">
<p className="p-text">
<span className="font-semibold">Normalization</span> is the process of
organizing a database to reduce redundancy and improve data integrity by
breaking large tables into smaller, well-structured ones.
</p>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Why Normalize?</span>
</h3>
<ul className="section-list">
<li><span className="font-semibold">Insertion Anomaly:</span> cannot add data without unrelated data. Example: can&apos;t add a course unless a student is enrolled.</li>
<li><span className="font-semibold">Deletion Anomaly:</span> deleting one record accidentally removes other useful data.</li>
<li><span className="font-semibold">Update Anomaly:</span> updating one value requires changing it in many places.</li>
<li>Normalization solves all three by removing redundant data dependencies.</li>
</ul>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Functional Dependency</span>
</h3>
<ul className="section-list">
<li>A <span className="font-semibold">Functional Dependency (FD)</span> means one attribute determines another. Written as A → B.</li>
<li>Example: StudentID → StudentName (knowing the ID tells you the name).</li>
<li><span className="font-semibold">Partial Dependency:</span> a non-key attribute depends on part of a composite primary key.</li>
<li><span className="font-semibold">Transitive Dependency:</span> a non-key attribute depends on another non-key attribute.</li>
</ul>
<div className="tip-block">
<p>Exam Tip: FDs are the foundation of all normal forms. Master them first.</p>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">1NF — First Normal Form</span>
</h3>
<ul className="section-list">
<li>A table is in 1NF if every column contains <span className="font-semibold">atomic (indivisible) values</span>.</li>
<li>No repeating groups or arrays in a single column.</li>
<li>Each row must be unique (has a primary key).</li>
</ul>
<div className="example-block">
<p className="font-semibold mb-1">Violation → Fix</p>
<pre>{`❌ Not 1NF:
StudentID | Courses
101 | DBMS, OS, CN

✅ 1NF:
StudentID | Course
101 | DBMS
101 | OS
101 | CN`}</pre>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">2NF — Second Normal Form</span>
</h3>
<ul className="section-list">
<li>Must be in 1NF.</li>
<li>No <span className="font-semibold">partial dependencies</span> — every non-key attribute must depend on the <span className="font-semibold">entire</span> primary key.</li>
<li>Applies only when the primary key is composite.</li>
</ul>
<div className="example-block">
<p className="font-semibold mb-1">Violation → Fix</p>
<pre>{`❌ Not 2NF (PK = StudentID + CourseID):
StudentID | CourseID | StudentName | Grade
101 | CS401 | Zubair | A

StudentName depends only on StudentID (partial dependency).

✅ 2NF: Split into two tables:
Students(StudentID, StudentName)
Enrollments(StudentID, CourseID, Grade)`}</pre>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">3NF — Third Normal Form</span>
</h3>
<ul className="section-list">
<li>Must be in 2NF.</li>
<li>No <span className="font-semibold">transitive dependencies</span> — non-key attributes must not depend on other non-key attributes.</li>
</ul>
<div className="example-block">
<p className="font-semibold mb-1">Violation → Fix</p>
<pre>{`❌ Not 3NF:
StudentID | DeptID | DeptName
101 | D01 | CSE

DeptName depends on DeptID (not on StudentID) — transitive.

✅ 3NF: Split:
Students(StudentID, DeptID)
Departments(DeptID, DeptName)`}</pre>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">BCNF — Boyce-Codd Normal Form</span>
</h3>
<ul className="section-list">
<li>A stricter version of 3NF.</li>
<li>For every FD A → B, A must be a <span className="font-semibold">superkey</span>.</li>
<li>Handles cases where 3NF still has anomalies due to overlapping candidate keys.</li>
</ul>
<div className="tip-block">
<p>If a table is in BCNF, it is also in 3NF — but not vice versa. BCNF is stronger.</p>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Decomposition</span>
</h3>
<ul className="section-list">
<li><span className="font-semibold">Lossless Join:</span> splitting a table and rejoining gives back the original data exactly.</li>
<li><span className="font-semibold">Dependency Preservation:</span> all original FDs can still be checked in the decomposed tables.</li>
<li>BCNF decomposition always gives lossless joins but may lose dependency preservation.</li>
<li>3NF decomposition preserves both lossless join and dependency preservation.</li>
</ul>
</section>
</div>
);
};
126 changes: 126 additions & 0 deletions app/sem4/dbms/content/chapter5.tsx
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export const Ch5Content = () => {
return (
<div className="course-content">
<p className="p-text">
A <span className="font-semibold">transaction</span> is a sequence of
database operations treated as a single unit. Concurrency control ensures
multiple transactions run simultaneously without conflicts.
</p>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">ACID Properties</span>
</h3>
<ul className="section-list">
<li><span className="font-semibold">Atomicity:</span> all operations succeed, or none do. No partial execution.</li>
<li><span className="font-semibold">Consistency:</span> the database moves from one valid state to another.</li>
<li><span className="font-semibold">Isolation:</span> concurrent transactions do not interfere with each other.</li>
<li><span className="font-semibold">Durability:</span> once committed, changes persist even after a crash.</li>
</ul>
<div className="tip-block">
<p>Exam Tip: ACID is one of the most asked topics. Remember all four with the mnemonic: <span className="font-semibold">A</span>ll <span className="font-semibold">C</span>hanges <span className="font-semibold">I</span>solated &amp; <span className="font-semibold">D</span>urable.</p>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Transaction States</span>
</h3>
<ul className="section-list">
<li><span className="font-semibold">Active:</span> transaction is currently executing.</li>
<li><span className="font-semibold">Partially Committed:</span> last operation executed, not yet written to disk.</li>
<li><span className="font-semibold">Committed:</span> all changes written permanently to the database.</li>
<li><span className="font-semibold">Failed:</span> normal execution cannot continue.</li>
<li><span className="font-semibold">Aborted:</span> transaction rolled back; database restored to previous state.</li>
</ul>
<div className="example-block">
<p className="font-semibold mb-1">State Flow</p>
<pre>{`Active → Partially Committed → Committed
Active → Failed → Aborted`}</pre>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Concurrency Problems</span>
</h3>
<ul className="section-list">
<li><span className="font-semibold">Lost Update:</span> two transactions read and update the same data; one update overwrites the other.</li>
<li><span className="font-semibold">Dirty Read:</span> a transaction reads data written by another transaction that has not committed yet.</li>
<li><span className="font-semibold">Unrepeatable Read:</span> a transaction reads the same row twice and gets different values because another transaction updated it.</li>
<li><span className="font-semibold">Phantom Read:</span> a transaction re-executes a query and finds new rows added by another transaction.</li>
</ul>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Locking</span>
</h3>
<ul className="section-list">
<li><span className="font-semibold">Shared Lock (S):</span> allows reading. Multiple transactions can hold a shared lock simultaneously.</li>
<li><span className="font-semibold">Exclusive Lock (X):</span> allows reading and writing. Only one transaction can hold it; no other locks allowed.</li>
<li>A transaction must acquire the appropriate lock before accessing data.</li>
</ul>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Two-Phase Locking (2PL)</span>
</h3>
<ul className="section-list">
<li>A protocol to ensure serializability (correct concurrent execution).</li>
<li><span className="font-semibold">Growing Phase:</span> locks are acquired; no lock is released.</li>
<li><span className="font-semibold">Shrinking Phase:</span> locks are released; no new lock is acquired.</li>
<li>2PL guarantees conflict serializability but can cause deadlocks.</li>
</ul>
<div className="tip-block">
<p>Once a transaction releases its first lock, it enters the shrinking phase and cannot acquire new locks.</p>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Deadlock</span>
</h3>
<ul className="section-list">
<li>A deadlock occurs when two or more transactions wait for each other to release locks — forming a cycle.</li>
<li><span className="font-semibold">Detection:</span> use a wait-for graph; a cycle means deadlock.</li>
<li><span className="font-semibold">Prevention:</span> use timestamps (wait-die or wound-wait schemes).</li>
<li><span className="font-semibold">Recovery:</span> abort one transaction (the victim) to break the cycle.</li>
</ul>
<div className="example-block">
<p className="font-semibold mb-1">Deadlock Example</p>
<pre>{`T1 holds Lock(A), waits for Lock(B)
T2 holds Lock(B), waits for Lock(A)
→ Deadlock! Neither can proceed.`}</pre>
</div>
</section>

<hr className="my-6 border-[#c7a669] opacity-40" />

<section>
<h3 className="section-heading">
<span className="section-subheading">Timestamp-Based Concurrency Control</span>
</h3>
<ul className="section-list">
<li>Each transaction is assigned a unique timestamp when it starts.</li>
<li>Operations are ordered by timestamp to ensure serializability.</li>
<li><span className="font-semibold">Wait-Die:</span> older transaction waits; younger is aborted (dies).</li>
<li><span className="font-semibold">Wound-Wait:</span> older transaction aborts the younger (wounds it); younger waits if it&apos;s older.</li>
</ul>
</section>
</div>
);
};