challenging database query

Consider the following table:

A B C D select?

1	FOO	A1	100	n
1	BAR	Z2	100	n
2	FOO	A1	101	y
2	BAR	Z2	101	y
3	FOO	A1	102	y
4	BAR	Z2	99	y
5	FOO	A1	99	n
6	BAR	Z2	98	n
7	FOO	AB	103	y
7	BAR	ZY	103	y

This table has the idea of "groups", that is, a group is defined as all of the words from B that have the same number A. The values in column C also matter- we want to select both groups A=7 and A=1 since they contain different values C. Note that the groups defined by A=1 and A=3 are distinct- they do not contain the same number of words from B, so we want to select them both. Also note that D is datetime, and all the rows with the same number A will have the same D (this is actually ensured by a single row in another table.)

I want to select all of the numbers A which define distinct groups and have the highest datetime D. Is this possible using a single query? Received on Wed Oct 03 2001 - 11:58:37 CDT