SINGLE ROW-FUNCTIONS

SINGLE ROW-FUNCTIONS
可以用於 SELECT NVL(), 或Where xx=nvl(),order by
可以修改 資料型態
--
http://ist.marshall.edu/ist466/functions.html
--
Any arithmetic operation on a NULL value results in a NULL. The same model is true for most functions as well. Only functions

    * NVL
    * NVL2
    * CONCAT
    * DECODE
    * DUMP
    * and REPLACE

can return non-NULL value when called with a NULL argument.