2010/11/24 Florian Weimer <fweimer@xxxxxx>: > * Grzegorz JaÅkiewicz: > >> just never use SELECT *, but always call columns by names. You'll >> avoid having to depend on the order of columns, which is never >> guaranteed, even if the table on disk is one order, the return columns >> could be in some other. > > This can't be true because several SQL features rely on deterministic > column order. ÂHere's an example: > > SELECT 1 AS a, 2 AS b UNION SELECT 3 AS b, 4 AS a; > > Âa | b > ---+--- > Â1 | 2 > Â3 | 4 > (2 rows) > Read again what I wrote please. Yes, most DBs do a good job to keep it consistent, but they don't have to. So unless you specify column names explicitly (like you did in the example above), there's no guarantees. Most people struggle with long table names in joins and stuff, for instance: SELECT foo.one, bar.two FROM foo join ... Because they forget about the aliases, like SELECT a.one, b.two FROM foo a JOIN bar b .. -- GJ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
