SQL Performance

SQL Date Filtering Returning Wrong Ranges: BETWEEN, Truncation, and Timezone Traps

SQL date filters often appear simple, yet subtle mistakes involving BETWEEN, timestamp truncation, time zones, and data types can return missing or unexpected rows. Learn why SQL date range queries fail and how to write reliable, high-performance date filters across modern relational databases.

Jul 30, 2026 5m read 👁 16

SQL DISTINCT vs GROUP BY: When Each One Silently Lies to You

DISTINCT and GROUP BY often appear to produce identical results, leading many developers to use them interchangeably. However, they solve different problems, and misunderstanding their behavior can produce incorrect reports, hidden duplicates, misleading aggregations, and poor query performance.

Jul 21, 2026 5m read 👁 2