CREATE PROCEDURE sp_transfer
@från INT,
@till INT,
@amount INT
AS
BEGIN
    BEGIN TRANSACTION
    @interest = @amount*0.03
    UPDATE S_Konto
    SET balans = balans - @amount - @interest
    WHERE NR = @från

    UPDATE S_Konto
    SET balans = balans + @amount
    WHERE NR = @till

    UPDATE S_Konto
    SET balans = balans + @interest
    WHERE NR = 1

    IF (SELECT balans FROM S_Konto
        WHERE NR = @från) <0
        ROLLBACK TRANSACTION
    ELSE
        COMMIT TRANSACTION
END