sql - COUNT() doesn't work with GROUP BY? - 


select count(*) table group column

i total number of rows table, not number of rows after group by. why?

because how group by works. returns 1 row each identified group of rows in source data. in case, give count each of groups.

to want:

select count(distinct column) table;

edit:

as slight note, if column can null, real equivalent is:

select (count(distinct column) +         max(case when column null 1 else 0 end)        ) table;

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