JORGE MALDONADO wrote > How does the EXCEPT work? Do fields should be identical? > I need the difference to be on the first 3 fields.
Except operates over the entire tuple so yes all fields are evaluated and, if they all match, the row from the "left/upper" query is excluded. If you need something different you can use some variation of: IN EXISTS NOT IN NOT EXISTS with a sub-query (correlated or uncorrelated as your need dictates). For example: SELECT col1, col2, col3, sum(col4) FROM tbl WHERE (col1, col2, col3) NOT IN (SELECT col1, col2, col3 FROM tbl2) -- not correlated GROUP BY col1, col2, col3 SELECT col1, col2, col3, sum(col4) FROM tbl WHERE NOT EXISTS ( SELECT 1 FROM tbl AS tbl2 WHERE --make sure to alias the sub-query table if it matches the outer reference (tbl.col1, tbl.col2, tbl.col3) = (tbl2.col1, tbl2.col2, tbl2.col3) ) -- correlated; reference "tbl" within the query inside the where clause GROUP BY col1, col2, col3 I do not follow your example enough to provide a more explicit example/solution but this should at least help point you in the right direction. David J. -- View this message in context: http://postgresql.1045698.n5.nabble.com/Select-statement-with-except-clause-tp5756658p5756661.html Sent from the PostgreSQL - sql mailing list archive at Nabble.com. -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
