sql - Why does the HAVING clause need to come after the GROUP-BY? -

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i want understand logically why need having clause after group-by ?

select name actor id in (     select actorid    casting    ord = 1  group actorid having count(*) > 29  ) order name asc

it hasn't clicked yet me, why following incorrect :

having count(*) > 29 group actorid

the reason because sql group records before evaluates having clause.

it sql syntax, makes intuitive sense, jeroen points out :

having applies result of grouping, in particular, unusual case, sql following chronological order of query steps.

10 tips sorting sql - techrepublic


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