My Web searching foo fails me, and I don't see the answer in the postgres docs so I hope someone here can point me in the proper direction. There is a table for bacteriological data that contains two columns for the date and time the water was collected and another two columns for the date and time the plates were read (since the latter should be less than 24 hours after the former). It would be simpler to combine each date-time pair into a single timestamptz column. Seems to me that this can be done with SQL within psql, but just how is not obvious to me because I've not worked with timestamp values before. What is the most parsimonious way to combine the two columns into one? TIA, Rich -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general