MYSQL Modify FOREIGN key support Cascade Delete

First of all must have the foreign key, InnoDB what does not say, directly on the change sentence.

To remove the foreign key first, then add it.

The specific reason seems to be because the alter foreign key operation is not supported.

 alter  table   ' t_terminal '  drop  foreign  key   alter  table   ' t_terminal '  add  constraint  ' fk704405e7f06a14ef ' foreign  key  (' userId ') references  ' T_ User ' (' id ') on  cascade  on  update  restrict ; 

MYSQL Modify FOREIGN key support Cascade Delete