怎么在SQL语句中对抽出的字段的值进行判断？

要求是这样的，举个例子**
SELECT A,B,C FROM TAB1 ,
要求如果A的值为0的话就显示为空，请问怎么加判断啊？在哪里加呢？

我已经写出来了，谢谢各位，还是跟大家分享一下
SELECT DECODE(A,'0','') AS A ,B AS B,C AS C FROM(SELECT A,B,C,D FROM TAB1)

select case A when 0 then "" else A end

SELECT case A when 0 then "" else cast(A as varchar(18)) end as A,B,C FROM TAB1
或者 SELECT case when A =0 then "" else cast(A as varchar(18)) end as A,B,C FROM TAB1
如果你的A本来存放的是数字（因为你说有等于零），那么你要把字段全转成字符型，不然记得会出错：）

select case A when 0 then "" else A ,B,C end from TAB1