[Solved] You wrote this query:SELECT Department, COUNT(*) FROM Employees GROUP BY Department HAVING Department IS NOT NULL;but it returns no rows for NULL... How can you fix it to include NULL group counts? | SQL

SQL - GROUP BY and HAVING

You wrote this query:
SELECT Department, COUNT(*) FROM Employees GROUP BY Department HAVING Department IS NOT NULL;
but it returns no rows for NULL departments. How can you fix it to include NULL group counts?

ARemove the HAVING clause to include NULL groups.

BChange HAVING to WHERE Department IS NOT NULL.

CAdd GROUP BY COALESCE(Department, 'Unknown').

DUse HAVING Department IS NULL instead.

Step-by-Step Solution

Solution:

Step 1: Understand HAVING clause effect
HAVING Department IS NOT NULL filters out NULL groups after grouping.
Step 2: Fix query to include NULL groups
Removing HAVING clause keeps all groups including NULL.
Final Answer:
Remove the HAVING clause to include NULL groups. -> Option A
Quick Check:
HAVING filters groups; remove to keep NULL [OK]

Quick Trick: HAVING filters groups; remove to keep NULL groups [OK]

Common Mistakes:

MISTAKES

Replacing HAVING with WHERE (wrong place)
Forgetting HAVING filters after grouping
Using HAVING IS NULL instead of IS NOT NULL

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You wrote this query:

Step 1: Understand HAVING clause effect

Step 2: Fix query to include NULL groups

Final Answer:

Quick Check:

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