SQL Fundamentals

SQL Fundamentals

SQL from first query to advanced patterns. SELECT, JOIN, GROUP BY, subqueries, window functions, indexes, transactions, and the SQL concepts every developer must know before touching any database.

BeginnerTopics 1–9
  • ·What is SQL & relational databases
  • ·SELECT & FROM
  • ·WHERE & filtering
  • ·ORDER BY & LIMIT
  • ·INSERT, UPDATE, DELETE
  • ·CREATE TABLE & data types
  • ·PRIMARY KEY & FOREIGN KEY
  • ·INNER JOIN
  • ·NULL handling
Start Beginner →
IntermediateTopics 10–18
  • ·LEFT, RIGHT & FULL OUTER JOIN
  • ·GROUP BY & aggregate functions
  • ·HAVING
  • ·Subqueries
  • ·UNION & UNION ALL
  • ·CASE expressions
  • ·String & date functions
  • ·Aliases & derived tables
  • ·IN, BETWEEN, LIKE (advanced)
Start Intermediate →
AdvancedTopics 19–27
  • ·Window functions — ROW_NUMBER, RANK
  • ·OVER, PARTITION BY & frame clauses
  • ·LAG & LEAD
  • ·Common Table Expressions (CTEs)
  • ·Recursive CTEs
  • ·Indexes
  • ·EXPLAIN & query plans
  • ·Transactions & ACID
  • ·Views & materialized views
Start Advanced →
PatternsTopics 28–35
  • ·Normalisation (1NF, 2NF, 3NF)
  • ·Many-to-many relationships
  • ·Pagination (OFFSET vs keyset)
  • ·Upsert (INSERT ... ON CONFLICT)
  • ·JSON in SQL (JSONB)
  • ·Full-text search
  • ·Stored procedures & functions
  • ·SQL interview patterns
Start Patterns →