From 128d006242dae07edc65ad03e0e045adac0bbbf3 Mon Sep 17 00:00:00 2001 From: Jon Leighton Date: Tue, 9 Aug 2011 00:12:53 +0100 Subject: Support updates with joins. Fixes #522. --- .../connection_adapters/abstract/database_statements.rb | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'activerecord/lib/active_record/connection_adapters/abstract') diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb index 2ae655e68d..7543d35d3b 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb @@ -306,6 +306,15 @@ module ActiveRecord end end + # The default strategy for an UPDATE with joins is to use a subquery. This doesn't work + # on mysql (even when aliasing the tables), but mysql allows using JOIN directly in + # an UPDATE statement, so in the mysql adapters we redefine this to do that. + def join_to_update(update, select) #:nodoc: + subselect = select.clone + subselect.ast.cores.last.projections = [update.ast.key] + update.wheres = [update.ast.key.in(subselect)] + end + protected # Returns an array of record hashes with the column names as keys and # column values as values. -- cgit v1.2.3