BEGIN - ROLLBACK - COMMIT TRANSACTION

BEGIN TRANSACTION;
update Table1
set column1 = 'value1'
where key = 1

update Table2
set column2 = 'value2'
where key = 2


--COMMIT

--ROLLBACK

-- First run with "BEGIN TRANSACTION"
-- If it was OK then run "COMMIT"
-- If it was not OK then run "ROLLBACK"