c# - 平均存储过程中的空列

Question

我有一个存储过程，我想对空列进行平均。

这是我的存储过程:

SELECT 
    AVG(planned) AS Planned,
    AVG(achieved) AS Achieved 
FROM 
    Port 
INNER JOIN 
    Technology ON Port.portID = Technology.portRef 

我使用数据源将此存储过程绑定(bind)到图表，当该列为空时，C# 代码抛出此错误:

Value was either too large or too small for a Decimal.

如何处理我的存储过程以avg那些空列？

Answer 1

当查询没有返回任何值时会发生这种情况。用这个

SELECT 
    coalesce(avg(planned),0) as Planned,
    coalesce(avg(achieved),0) as Achieved 
FROM 
    Port inner join Technology on Port.portID = Technology.portRef