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From: davids@stsci.EDU (David Silberberg)
Newsgroups: comp.databases
Subject: How do you do this query?
Keywords: SQL, query
Message-ID: <940@cirrus.stsci.edu>
Date: 19 Nov 89 23:23:44 GMT
Organization: Space Telescope Science Institute, Baltimore, MD 21218
Lines: 39

How do you do the following query in SQL?

Imagine a table of the following:

	A	B	C
      ---------------------
	z	y	1
	z	y	2
	z	y	3
	w	y	1
	w	y	2
	x	p	1
	x	z	1
	x	z	2
	x	z	3
	etc.

If I did a 'select A, B, C from table where B="y" ', I would get the following:

	A	B	C
      ---------------------
	z	y	1
	z	y	2
	z	y	3
	w	y	1
	w	y	2

What I really want is a select that would get only the line with the
maximum value of C for each unique combination of A, B.  It would
produce the following:

	A	B	C
      ---------------------
	z	y	3
	w	y	2

Remember, only SQL standard queries allowed. 

Thanks in advance.
David Silberberg