So update it, then update it back?
Update MyTable
SET City = 'B'
WHERE City = 'A';
Update MyTable
SET City = 'A'
WHERE City = 'B';
You can't do it in one statement, because updating a column to one value and then updating it to another require two statements. Though you could just have a single statement that does nothing and it'll have the same effect.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability