On Fri, Dec 14, 2012 at 7:22 AM, John R Pierce <pie...@hogranch.com> wrote: > On 12/13/2012 5:32 AM, seil...@so-net.net.tw wrote: >> >> I am trying to implement a mechanism that prohibits the last row of a data >> set from being deleted. >> >> CREATE TABLE t1 (c1 INTEGER,c2 INTEGER, PRIMARY KEY (c1,c2)); >> >> INSERT INTO t1 VALUES (1,1),(1,2),(1,3),(2,1),(2,2),(2,3); > > > Which row is the last row? relations are sets, not ordered lists.
My understanding of the OP is that this is a constraint whereby there must always be at least one remaining row for a given value of c1. That is to say, you may delete any row from t1 as long as it's not the last row (temporally, not sequentially) with that c1. ChrisA -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
