method

join_to_update

v4.2.7 - Show latest stable - 0 notes - Class: ActiveRecord::ConnectionAdapters::DatabaseStatements

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What's this?

join_to_update(update, select) public

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.

Show source

# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 332
      def join_to_update(update, select) #:nodoc:
        key = update.key
        subselect = subquery_for(key, select)

        update.where key.in(subselect)
      end

join_to_update

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