mysql> create table tb_test (id int(10) not null auto_increment primary key,action_id int(10) not null,error_code int(10) not null default 0,desc_key varchar(64) not null default ‘audit.log.default‘,INDEX(action_id),constraint `FK_ACTIONID` foreign key(`action_id`) references `tb_tab1` (`action_id`));
ERROR 1215 (HY000): Cannot add foreign key constraint
mysql>
定位方法如下：
SHOW ENGINE INNODB STATUS:
LATEST FOREIGN KEY ERROR
------------------------
2016-01-29 08:45:15 7f5b11b09700 Error in foreign key constraint of table auditdb/tb_test:
foreign key(`action_id`) references `tb_tab1` (`action_id`)):
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
很详细
Mysql create constraint foreign key faild.trouble shooting method share
原文：http://www.cnblogs.com/dogharry/p/5169460.html