Ladislav Lenart wrote > * Should I alias one of the references to deal? > * The above query works the same both with and without an alias, so is it > simply > a matter of taste / good practice? > * Where can I find more info about this, i.e. when the alias is mandatory > and > when it is only a convenience? I've scanned through > > > http://www.postgresql.org/docs/9.1/static/queries-table-expressions.html > > but it only mentions that subselect in FROM must have an alias. I would > like to > know about IN (...) and EXISTS (...). Aliases are mandatory for self-joins. Basically two relations at the same query level cannot have the same name. With sub-selects the inner level shields the outer level from being visible so an alias is optional. I believe the case of a correlated sub-query requires the alias for the same reason - otherwise you end up with a always true where clause when joining the supposed two deal tables together. There is no right/best way but it is always more clear to rename such that you avoid repeating the same relation name in the query. David J. -- View this message in context: http://postgresql.1045698.n5.nabble.com/Q-Table-aliasing-tp5773355p5773364.html Sent from the PostgreSQL - general mailing list archive at Nabble.com. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
