SQL

CREATE TABLE, Data Types & Constraints

Primary Key & Foreign Key Constraints

ALTER TABLE

Creating Indexes

Views & Materialized Views

Stored Procedures & Functions in SQL

Transactions & Savepoints in SQL

SELECT & WHERE Clause

ORDER BY, LIMIT & OFFSET

DISTINCT, BETWEEN, IN & LIKE

NULL Handling

CASE Expressions

String Functions

Date/Time Functions

INSERT, UPDATE & DELETE

INNER JOIN

LEFT & RIGHT OUTER JOIN

FULL OUTER JOIN & UNION Emulation

SELF JOIN

CROSS JOIN

Joining 3+ Tables

JOIN Performance

Anti-JOIN Pattern

GROUP BY ROLLUP & CUBE

GROUPING SETS

DISTINCT vs GROUP BY

COUNT(DISTINCT col) & Approximate Counting

HAVING vs WHERE

COUNT, SUM, AVG, MIN, MAX Deep Dive

Scalar Subquery

Correlated Subquery

IN vs EXISTS vs ANY vs ALL

CTE (WITH Clause)

Recursive CTE

Subquery vs JOIN vs CTE — When to Use Which

LATERAL JOIN / CROSS APPLY

Derived Tables

Window Function Basics

ROW_NUMBER, RANK & DENSE_RANK

LEAD & LAG

FIRST_VALUE & LAST_VALUE

NTILE

Running Totals & Moving Averages

Window Functions vs GROUP BY

B-Tree Index Internals

Composite Index & Column Order

Covering Index & Index-Only Scans

Index Selectivity & Cardinality

EXPLAIN / EXPLAIN ANALYZE

Query Optimization Patterns