SQL CE DISTINCT AGGREGATE

问题

Does SQL CE has the ability to use distinct in aggregate functions? I need something like

SELECT count(distinct date) FROM table

This is simplified query and I already have GROUP BY used in original one.

回答1:

SQL Server CE (current version) does not support count(distinct)

The workaround is a GROUP BY, which sounds like what you are using

select count(*) from (
    select distinct date from tbl
) x

Or if other fields are involved

select groupcol, count(*)
from (
    select groupcol, date
    from tbl
    group by groupcol, date
) x
group by groupcol

来源：https://stackoverflow.com/questions/5064592/sql-ce-distinct-aggregate