SQL Debugging

SQL CTEs vs Subqueries: Why Your Query Returns Different Row Counts

Are your SQL CTE and subquery versions returning different row counts? Learn why this happens, how query logic, joins, filtering, and execution plans affect results, and how to debug row count discrepancies across major SQL databases.

Oct 15, 2026 6m read 👁 2

SQL NULL Comparisons Returning Wrong Results: IS NULL vs = NULL Traps

One of the most common SQL mistakes is comparing NULL values using = NULL instead of IS NULL. The result is queries that silently return incorrect or empty result sets. Learn why SQL treats NULL differently, understand three-valued logic, and write reliable queries that correctly handle missing data

Jul 01, 2026 4m read 👁 33