IF Statements

Example:

DECLARE
    l_sales_amt NUMBER := 60000;
    l_commission NUMBER;
BEGIN
    IF l_sales_amt > 50000 THEN
        l_commission := 10;
    ELSIF l_sales_amt > 40000 THEN
        l_commission := 5;
    ELSE
        l_commission := 2;
    END IF;
END;

Note that NULL does not evaluate as 0:

DECLARE
    l_sales_amt NUMBER;
    l_commission NUMBER := 0;
BEGIN
    -- Without IS NULL check, would erroneously assign commission of 10
    IF l_sales_amt < 25000 OR l_sales_amt IS NULL THEN
        l_commission := 2;
    ELSIF l_sales_amt < 35000 THEN
        l_commission := 5;
    ELSE
        l_commission := 10;
    END IF;
END;