How to swap values of two rows in MySQL without violating unique constraint?

Question

I have a \"tasks\" table with a priority column, which has a unique constraint.

I\'m trying to swap the priority value of two rows, but I keep violating the constrai

Answer 1

Had a similar problem.

I wanted to swap 2 id's that were unique AND was a FK from an other table.

The fastest solution for me to swap two unique entries was:

1. Create a ghost entry in my FK table.
2. Go back to my table where I want to switch the id's.
3. Turned of the FK Check SET FOREIGN_KEY_CHECKS=0;
4. Set my first(A) id to the ghost(X) fk (free's A)
5. Set my second (B) id to A (free's B)
6. Set A to B (free's X)
7. Delete ghost record and turn checks back on. SET FOREIGN_KEY_CHECKS=1;