Jeff Dean's Ruby Blog - Using MySQL foreign keys, procedures and triggers with Rails

Jeff Dean's Ruby Blog - Using MySQL foreign keys, procedures and triggers with Rails (via Instapaper)

module ForeignKeys def add_foreign_key(from_table, from_column, to_table, options = {}) to_column = options.fetch(:to_column, 'id') suffix = options[:suffix] on_delete = options[:delete] on_update = options[:update] on_delete = 'SET NULL' if on_delete == :set_null on_update = 'CASCADE' if on_update == :cascade constraint_name = "fk_#{from_table}_#{to_table}" constraint_name += "_#{suffix}" unless suffix.nil? sql = "ALTER TABLE #{from_table} ADD CONSTRAINT #{constraint_name} FOREIGN KEY (#{from_column}) REFERENCES #{to_table}(#{to_column})" sql += "\nON DELETE #{on_delete}" if on_delete sql += "\nON UPDATE #{on_update}" if on_update execute sql end def remove_foreign_key(from_table, to_table, suffix = nil) constraint_name = "fk_#{from_table}_#{to_table}" constraint_name += "_#{suffix}" unless suffix.nil? # note, you may have to use DROP KEY here - see MySQL docs for details...

Full article: http://pivotallabs.com/users/jdean/blog/articles/1707-usi...