Cannot Drop A Foreign Key In MySQL

It's a common example between Persons and Orders. I just copied it from Internet as a test. CREATE TABLE Persons ( ID int NOT NULL, LastName varchar(255) NOT NULL, F

Solution 1:

Identify the name of the constraint using the statement:

SELECT CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE TABLE_NAME = 'Orders'
AND COLUMN_NAME = 'PersonID';

Use the result from CONSTRAINT_NAME in your ALTER TABLE statement. For example:

ALTER TABLE Orders
DROP FOREIGN KEY `myconstraint`;

Answer derived from the MySQL Reference Manual

Solution 2:

you need to delete constraint and also the key. First find the constraint by doing the following

1) SHOW CREATE table Orders;

pick up value of CONSTRAINT.. in this screenshot 'fk_dayBreakUp_timetable'

2) ALTER TABLE Orders DROP foreign key << constraint_name >>

here you would do

3) ALTER TABLE Orders DROP key << column name >>

Hope this resolves your issue.