DISTINCT on multiple columns

I have, SELECT DISTINCT (first),second,third FROM 开发者_StackOverflow社区table

AND i want not only the first to be DISTINCT and the second to be DISTINCT to but the third to stay without DISTINCT , i tryed like that.

SELECT DISTINCT (first,second),third FROM table

And couple more things but didnt worked.

SELECT  m.first, m.second, m.third -- and possibly other columns
FROM    (
        SELECT  DISTINCT  first, second
        FROM    mytable
        ) md
JOIN    mytable m
ON      m.id =
        (
        SELECT  id
        FROM    mytable mi
        WHERE   mi.first = md.first
                AND mi.second = md.second
        ORDER BY
                mi.first, mi.second, mi.third
        LIMIT 1
        )

Create an index on (first, second, third) for this to work fast.

Have you seen this post?

Select distinct from multiple fields using sql

They seem very similar, maybe you could try something like that?

Hope this helps!