Looks like I don't have this fixed, so I have re-added it to the FAQ.

test=> create table xx (x int, y int) ;     
CREATE
test=> insert into xx select usesysid, count(*) from pg_user group by
usesysid;
ERROR:  The field being grouped by must appear in the target list

In this case, the group by the parser is checking for is x and y, not
the results of the select, so it fails.

-- 
Bruce Momjian                          |  830 Blythe Avenue
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Sun, 1 Mar 1998 00:40:31 -0500 (EST)
Bruce Momjian <maillist@candle.pha.pa.us>
INSERT with GROUP