SQL Interview Prep · Lesson

HAVING vs WHERE

Filtering before grouping versus after, and which clause sees the aggregate.

The Question You Will Get

'What is the difference between WHERE and HAVING?' is one of the most asked SQL interview questions. A weak answer says 'HAVING is for aggregates.' A strong answer explains when each clause runs in the query pipeline.

That timing is the whole story: WHERE filters rows before grouping; HAVING filters groups after aggregation.

Where They Sit in Execution Order

Recall the logical execution order of a query:

FROM / JOIN → build the row set
WHERE → filter individual rows
GROUP BY → collapse into groups
HAVING → filter the groups
SELECT → project columns
ORDER BY → sort

WHERE happens before groups exist; HAVING happens after, so HAVING can see aggregates and WHERE cannot.

All lessons in this course

The GROUP BY Rule for SELECT Columns
HAVING vs WHERE
Grouping by Multiple Columns and Expressions
Counting and Filtering Groups

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