Hi, Alexey! On Jan 31, Alexey Botchkov wrote:

...

can a CHECK constraint have the same name as an existing FK?

Yes, it can. So in this case the 'ALTER ... DROP CONSTRAINT c' drops the FOREIGN KEY. On the second call this ALTER removes the CHECK. How do you like that? I think it's ok as the very idea of same names for constraints seems sick.

Let's handle it separately. Could you please report it as a bug? A table shouldn't have two constraints with the same name.

...

what about UNIQUE constraint?

The 'ALTER TABLE ADD CONSTRAINT UNIQUE unique_key' just adds UNIQUE key. So i'm in doubt how we should handle the 'DROP CONSTRAINT unique_key' statement.

By dropping the unique key, why, is there another option? UNIQUE index is a constraint, not just an optimization helper, like a non-unique index. You already have a loop over all drop constraints, checking for unique shouldn't be a problem. It should drop PRIMARY KEY too, I suppose. We allow ADD CONSTRAINT PRIMARY KEY. Regards, Sergei Chief Architect MariaDB and security@mariadb.org