PostgreSQL

Security notes, SOC lab write-ups and tested code by Mahir Faysal, a SOC Level 1 cybersecurity learner in Bangladesh, plus notes from my Next.js and Gemini projects. Sample posts are marked and drafts stay in the admin area.

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Coding tips

SQL WHERE vs HAVING: Differences, Execution Order and When to Use Each (Tested Examples)

WHERE filters individual rows before GROUP BY, while HAVING filters the groups after it and can use aggregates like SUM() and COUNT(). Here is how they differ, with real results, errors and query plans from MySQL 8.4, PostgreSQL 17 and SQLite 3.46.

November 4, 2026 · 13 min read · 1 view