Question

table有a,b,c三个字段，类型为数值。oracle查出每行这3个字段值的平均值，为空的排除。比如a,b,c都有值

就是：select (a+b+c)/3 from table那如果a为空呢，

Answer 1

sqlserver select (isnull(a,0)+b+c) /3from table

用isnull函数
如果a为空的时候,就默认成0
isnull(a,0)

oracle得用nvl函数

select (nvl(a,0)+b+c) /3from table

Answer 2

select (isnull(a,0)+isnull(b,0)+isnull(c,0))/
(SELECT COUNT(*) FROM
(SELECT ISNULL(A,0) A FROM TALBE
UNION ALL
SELECT ISNULL(B,0) A FROM TALBE
UNION ALL
SELECT ISNULL(C,0) A FROM TALBE ) T

WHERE A<>0)

FROM TALBE

Answer 3

ORACLE 数据库
select (nvl(a,0)+nvl(b,0)+nvl(c,0))/3 from table

Answer 4

同意1楼和3楼。isnull(a,0)