How to delete foreign key in mysql?

Question

I have tried both the syntaxes:

Alter Table bc DROP FOREIGN KEY STUD_ID;

It is giving the error: Can't DROP 'STUD_ID'; check that column/key exists

Alter Table bc DROP CONSTRAINT STUD_ID;

It is giving the error:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'CONSTRAINT STUD_ID' at line 1

Suggest me the possible ways.

Answer 1

ALTER TABLE TableName DROP FOREIGN KEY ForeignKeyConstraintName;

希望这可以帮助 ：）

Answer 2

Your first query works. It is telling you that there is no such key to drop. This means your key has another name. It has not the same name as the column it indexes. Run

show index from bc

to show all key names and then run your query again with the correct name

Alter Table bc DROP FOREIGN KEY <STUD_ID_index_name>

Answer 3

alter table bc drop foreign key forconstraintname