What is Compare HAVING to WHERE

While both HAVING and WHERE clauses filter data, remember that WHERE operates on rows returned by the FROM clause. If a GROUP BY … HAVING section exists in your query following a WHERE clause, the WHERE clause will filter rows before GROUP BY is processed—potentially limiting the groups that can be created.

A HAVING clause is processed after GROUP BY and only operates on groups, not detail rows. To summarize:

• A WHERE clause filters rows before any groups are formed
• A HAVING clause filters entire groups, and usually looks at the results of an aggregation.