关于DECODE 函数？ WHY!

DL-GreatWall

看了官方文档，没找到答案
create or replace view test as
select
        null DISCHARGE_DATE,
'1AB' AS VALUE,
   
        '1' AS FLAG,
        null AS DEPT
FROM dual
------------------------------------


select decode(flag, 1, count(distinct value), 2, sum(value), null)  from test

doni

sum(value)错了，value=‘1AB'

li0924

请把 null 换为 0；null并非数字