MySQL有两种常用的引擎类型:MyISAM和InnoDB。目前只有InnoDB引擎类型支持外键约束。InnoDB中外键约束定义的语法如下: ALTER TABLE tbl_name ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (index_col_name, ...) REFERENCES tbl_name (index_col_name,...) [ON DELETE reference_option] [ON UPDATE reference_option] 例如: ALTER TABLE `user_resource` CONSTRAINT `FKEEAF1E02D8… Read More