The difference between
HAVING and WHERE Here's another way to look it:
WHERE filters before data is grouped, and HAVING filters after
data is grouped. This is an important distinction; rows that are eliminated by a
WHERE clause will not be included in the group. This could change the
calculated values which in turn could affect which groups are filtered based on
the use of those values in the HAVING clause.
Using HAVING and
WHERE HAVING is so similar to WHERE that most
DBMSs treat them as the same thing if no GROUP BY is specified.
Nevertheless, you should make that distinction yourself. Use HAVING
only in conjunction with GROUP BY clauses. Use WHERE for
standard row-level filtering.
BTW:
The only difference is that WHERE filters rows and HAVING
filters groups.
The difference between HAVING and
WHERE Here's another way to look it: WHERE filters
before data is grouped, and HAVING filters after data is grouped.
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