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This prompted me to go look it up, since I didn't know. HAVING is WHERE for aggregate functions (SUM, etc).

Funny thing is, I've used HAVING a lot in the past, but couldn't have explained the difference succinctly without cheating and looking it up.

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Conceptually WHERE is filtering the table rows that get considered and HAVING is filtering the result rows - functions and all - that get returned. That's how my mental model of it all works.

I deal with pretty complex queries daily, and I completely forgot what HAVING did exactly. I guess it's because I long ago realized that if I had to use HAVING in a query, I'm doing something wrong. That's almost always a Reporting/BusIntel tool's job, not mine.

That's a great point. Part of learning SQL is learning what parts of it _not_ to use. Things like HAVING and ORDER BY are useful for ad hoc queries at a SQL command-line, but are either not useful or a waste when there's another level in the system like a BI tool.

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