SQL Foundations

Understand what SQL is and learn to read data using simple SELECT queries.

Learn SELECT basics, column order, aliases, and DISTINCT.

Use WHERE with AND/OR to filter rows by conditions.

Sort rows with ORDER BY and restrict output with LIMIT.

Use LIKE, IN, and BETWEEN for pattern and range filtering.

Use functions and expressions to transform and calculate data.

Summarize data with COUNT, SUM, AVG, MIN, and MAX.

Group rows and filter grouped results with HAVING.

Combine rows from two tables using INNER JOIN.

Keep unmatched rows with LEFT, RIGHT, and FULL joins.

Work safely with missing values using IS NULL and COALESCE.

Use subqueries to solve complex problems step-by-step.

Use window functions for ranking, running totals, and comparisons.

Understand how SQL executes clauses under the hood.

Learn INSERT, UPDATE, and DELETE with safe preview exercises.

Understand DDL with CREATE, ALTER, and DROP using schema previews.

Learn how indexes speed up queries and when to use them.

Solve high-frequency interview SQL problems across companies.