代码
alter table sfk_son_module add constraint foreign key(father_module_id) references sfk_father_module(id) on delete restrict on update restrict;
(constraint 后面可以加上约束名字)
错误原因是之前两张表的id的类型不一样,一个时int,一个时bigint
解决办法时修改表,
alter table sfk_father_module modify id bigint;
修改之后就可以了
下面是mysql的一些资料
ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name
[alter_specification [, alter_specification] ...]
[partition_options]
ADD [CONSTRAINT [symbol]]
FOREIGN KEY [index_name] (index_col_name,...)
reference_definition
Topic: CONSTRAINT
SQL supports foreign keys, which let you cross-reference related data across tables, and foreign key constraints, which help keep this spread-out data consistent. The essential syntax for a foreign key constraint definition in a CREATE TABLE or ALTER TABLE statement looks like this:
[CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name,...)
[ON DELETE reference_option]
[ON UPDATE reference_option]
reference_option:
RESTRICT | CASCADE | SET NULL | NO ACTION
See also: Online help create-table-foreign-keys
mysql为表添加外键完成性约束 报错Can't create table 'sfkbbs.#sql-513_25' (errno: 150)