DECLARE @amount decimal(18,2) = 1000
UPDATE account
    SET balance = balance +  @amount WHERE accountID= 1;
UPDATE account
    SET balance = balance -  @amount WHERE accountID= 2;

DECLARE @amount decimal(18,2) = 1000
   UPDATE account
        SET balance = balance +  @amount WHERE accountID= 1;
    AND
        SET balance = balance -  @amount WHERE accountID= 2;