What Is SQL and How Does It Work

Learn how the SQL SELECT statement works, including selecting columns, filtering rows, sorting results, aliases, expressions, and practical query patterns.

Learn how SQL joins work with simple beginner-friendly examples covering INNER JOIN, LEFT JOIN, common relationship patterns, matching rows between tables, and the mistakes new SQL users make most often.

Learn how the SQL WHERE clause works, including comparison operators, AND and OR logic, IN, BETWEEN, LIKE, NULL handling, filtering best practices, and common mistakes that cause wrong query results.

Learn how SQL window functions work, including OVER, PARTITION BY, ranking, running totals, moving averages, LAG, LEAD, and analytics patterns.