Re: count & distinct
От | Vashenko Maxim |
---|---|
Тема | Re: count & distinct |
Дата | |
Msg-id | 3948BD24.12C66D59@nino.ru обсуждение исходный текст |
Ответ на | count & distinct ("Andrea Aime" <aaime@comune.modena.it>) |
Список | pgsql-general |
Andrea Aime wrote: > > Hi people. I would like to make a query that > tells me how many distinct values there are > in a column. Standard count doesn't seems > to support a count distinct option. > select distint count(*) of course doens't > work (distinti clause is applied after the > result are calculated). I've tried to define > a view, but it didn't worked ( > create view distValues as select distinct ... > but views doesn't support distinct clause)... > > Well, maybe I should create a new aggregate > function, but before spending time on PGSQL > guide I would like to know if someone can > give me a fast tip... ;-) > Thanks in advance > Andrea > > PS: well, of course I can open a cursor on > a "select distinct column from table" and then > loop over the cursor couting how many values > there are, but it seem a bit ugly... SELECT field, count(*) FROM table GROUP BY field With best regards, Max Vaschenko, Nizhny Novgorod Information Networks.
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