16 / 65 · 15 SQL & Database Testing · JOINs and Aggregation← prev⊞ allnext →☰ Read as one page
2.8Key Takeaways
- LEFT JOIN finds orphaned records and missing relationships
- GROUP BY + HAVING reveals duplicates, patterns, and distributions
- Subqueries answer "compared to what?" questions (above average, never ordered)
- Use JOINs in test automation to cross-validate API data against the database
- Error analysis queries are invaluable for post-incident investigation