I'm not sure how to do that because a single UPDATE statement only has one WHERE clause. You'd have to come up with an expression to put in the SET part that gives the right values for different rows.
I guess you can always swap pairs of rows with subtraction, like swapping row 5 and 7 would be:
update t set user_order = 5 + (7 - user_order) where id in (123, 456)
Maybe you could use case statements to make an enumerated function in the more general case of updating multiple rows, but that's a bit ugly.
I guess you can always swap pairs of rows with subtraction, like swapping row 5 and 7 would be:
Maybe you could use case statements to make an enumerated function in the more general case of updating multiple rows, but that's a bit ugly.