method

join_to_update

v3.1.0 - 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 339
      def join_to_update(update, select) #:nodoc:
        subselect = select.clone
        subselect.projections = [update.key]

        update.where update.key.in(subselect)
      end

join_to_update

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