Question

This is my table offs:

date ----------   oid ------   head -----  cnt

2012-1-9 -----13      --------  10   -----------1
2012-1-11 --- 13      --------  6  -----------  2
2012-1-22 --- 13      --------  10   -----------3
2012-1-22 --- 11      --------  10   -----------4

I need a select function with a result the max(date) from oid and distinct head, like that:

2012-1-11 --- 13      --------  6  -----------  2
2012-1-22 --- 13      --------  10   -----------3
2012-1-22 --- 11      --------  10   -----------4

Answer 1

How about this query:

SELECT a.*, b.cnt from(
SELECT MAX(Date) AS Date, oid, head
from offs group by oid, head
)a inner join offs b on a.Date=b.Date and a.oid=b.oid and a.head=b.head