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Why is HAVING clause used only after GROUP BY?

SQLmedium0.4 min readPremium
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1,863
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Fossil Group
Expert AnswerPremium
87 wordsInterview-ready
HAVING filters **groups** after aggregation; WHERE filters **rows** before aggregation. **Why order matters**: HAVING operates on aggregated values (SUM, COUNT, AVG) that don't exist until after GROUP BY. Example: SELECT dept, AVG(sal) FROM emp GROUP BY dept HAVING AVG(sal) > 50000. You can't use WHERE AVG(sal) > 50000 because aggregates aren't computed yet. **Logical order**: FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY....
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