database - MySQL: why foreign key is not deleted after constraint deleting? -


after add foreign key command:

alter table_name add constraint constraint_name foreign key foreign_key_name(columns) references parent_table(columns) on delete action on update action;

we have table constraint 'constraint_name' , key 'foreign_key_name'.

after delete foreign key:

 alter table table_name  drop foreign key constarint_name

we have table key 'foreign_key_name', constraint deleted.

1) why key alive? how key deleting (after constraint deleting) affect working capacity? 2) why key not deleted constraint deleting?


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