What is a statutory constraint?

MySQL: #1064 when adding more than 1 constraint on foreign keys?

• I've checked it out for 4 times and didn't find any syntax error. Asking for help here and thx!!!! and my MySQL version is 5.5 (for better format, go here: http://stackoverflow.com/questions/13863758/mysql-1064-when-add-more-than-1-constraint-on-foreign-keys) error message is: 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ADD CONSTRAINT fk_notification_source_idFOREIGN KEY (source_id) REFERENCES ' at line 1 CREATE TABLE IF NOT EXISTS `object_type` (  `type_id` tinyint(1) NOT NULL,    `type_name` varchar(45) NOT NULL,  `desc` varchar(45) NOT NULL,  PRIMARY KEY (`type_id`)   ) ENGINE=InnoDB DEFAULT CHARSET=utf8 ;CREATE TABLE IF NOT EXISTS `op_type` (  `type_id` tinyint(1) NOT NULL,  `type_name` varchar(45) NOT NULL,  `desc` varchar(45) NOT NULL,  PRIMARY KEY (`type_id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8 ;CREATE TABLE IF NOT EXISTS `user_op` (  `op_id` int(11) NOT NULL AUTO_INCREMENT,  `user_id` int(11) NOT NULL,  `op_type` tinyint(1) NOT NULL,  `op_data` varchar(45) NOT NULL,    `time` datetime NOT NULL,  PRIMARY KEY (`op_id`, `user_id`),  KEY `fk_op_user_id_idx` (`user_id`),  KEY `fk_op_op_type_idx` (`op_type`)) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;CREATE TABLE IF NOT EXISTS `notification_type` (  `type_id` int(11) NOT NULL,  `type_name` varchar(45) NOT NULL,    `desc` varchar(45) NOT NULL,    PRIMARY KEY (`type_id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8;CREATE TABLE IF NOT EXISTS `user_notification` (  `notif_id` int(11) NOT NULL,    `user_id` int(11) NOT NULL,  `notif_type` int(11) NOT NULL,  `source_id` int(11) NOT NULL,    `path` varchar(45) NOT NULL,  `parent_id` int(11) NOT NULL,  `parent_type` tinyint(1) NOT NULL,  `count` int(11) NOT NULL,  `time` datetime NOT NULL,    `lasttimeread` datetime NOT NULL,  PRIMARY KEY (`notif_id`, `user_id`),  KEY `fk_notification_user_id_idx` (`user_id`),  KEY `fk_notification_type_id_idx` (`notif_type`),  KEY `fk_notification_source_id_idx` (`source_id`),  KEY `fk_notification_parent_type_idx` (`parent_type`)) ENGINE=InnoDB DEFAULT CHARSET=utf8;ALTER TABLE `user_op`  ADD CONSTRAINT `fk_op_user_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`user_id`) ON DELETE NO ACTION ON UPDATE NO ACTION,  ADD CONSTRAINT `fk_op_op_type` FOREIGN KEY (`op_type`) REFERENCES `op_type` (`type_id`) ON DELETE NO ACTION ON UPDATE NO ACTION;ALTER TABLE `user_notification`  ADD CONSTRAINT `fk_notification_user_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`user_id`) ON DELETE NO ACTION ON UPDATE NO ACTION,  ADD CONSTRAINT `fk_notification_type_id` FOREIGN KEY (`notif_type`) REFERENCES `notification_type` (`type_id`) ON DELETE NO ACTION ON UPDATE NO ACTION,  ADD CONSTRAINT `fk_notification_source_id` FOREIGN KEY (`source_id`) REFERENCES `user_op` (`op_id`) ON DELETE NO ACTION ON UPDATE NO ACTION,  ADD CONSTRAINT `fk_notification_parent_type` FOREIGN KEY (`parent_type`) REFERENCES `object_type` (`type_id`) ON DELETE NO ACTION ON UPDATE NO ACTION; thank you!!!

• Answer:

  I see two FK references to the user table ALTER TABLE `user_op`  ADD CONSTRAINT `fk_op_user_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`user_id`) ON DELETE NO ACTION ON UPDATE NO ACTION ADD CONSTRAINT `fk_notification_user_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`user_id`) ON DELETE NO ACTION ON UPDATE NO ACTION Do you need both?