MySQL外键陷阱

今天发现按照标准SQL写法在MySQL建表时创建的外键都没有生效 ，调查发现MySQL居然没有创建外键（使用的是最新的MySQL 5.7）。

mysql> create table tbp(id int,pid int REFERENCES tb(id) on delete RESTRICT);
Query OK, 0 rows affected (0.05 sec)

mysql> show create table tbp;
+-------+-----------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-----------------------------------------------------------------------------------------------------------------------+
| tbp | CREATE TABLE `tbp` (
  `id` int(11) DEFAULT NULL,
  `pid` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-----------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

换一种写法可以成功

mysql> create table tbp2(id int,pid int, FOREIGN KEY (pid) REFERENCES tb(id) on delete RESTRICT);
Query OK, 0 rows affected (0.04 sec)

mysql> show create table tbp2;
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tbp2 | CREATE TABLE `tbp2` (
  `id` int(11) DEFAULT NULL,
  `pid` int(11) DEFAULT NULL,
  KEY `pid` (`pid`),
  CONSTRAINT `tbp2_ibfk_1` FOREIGN KEY (`pid`) REFERENCES `tb` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

这也太坑了，不支持就应该报个错啊！