He wants to do the equivalent of a multiple assignment, where the sequence of values (1, 2, 3, 4, 5) becomes the new sequence (2, 3, 4, 5, 6). To the OP: Your update would succeed if done in the opposite order. Whether that can be made to happen reliably is an issue, but no more of an issue than with your example that does happen to work (SET id=id-1) by accident of the order in which the updates occur.