Cascade, NO ACTION, Restrict, set NULL in MySQL foreign key settings

1. Cascade Way
Synchronize update/delete out a matching record of a child table when Update/delete records on the parent table

2. Set NULL mode
Set the column of the matching record on the child table to NULL when the record is update/delete on the parent table
Note that the foreign key column of the child table cannot be not NULL

3. No Action Mode
If there are matching records in the child table, the Update/delete action is not allowed for the parent table corresponding to the candidate key

4. Restrict mode
Same no action, check foreign KEY constraints immediately

5. Set default mode
When a parent table has a change, the child table sets the foreign key column to a default value but InnoDB does not recognize

Reprint: http://blog.sina.com.cn/s/blog_91339bff0100ymc2.html

Cascade, NO ACTION, Restrict, set NULL in MySQL foreign key settings