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 in a SQL query? ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
