SSRS 自定义函数和 Null 值

Question

我正在尝试使用自定义函数来确定指标的值。问题是传递给函数的字段可以为 NULL。我使参数的类型可以为空，但它不会让我进行任何比较。我不知道为什么。

错误是"There is an error on line 20 of custom code: [BC30452] Operator '<' is not defined for types 'System.Nullable(Of Single)' and 'System.Nullable(Of Single)'."

Public Function GetIndicator(ByVal HistBal As Nullable(of single),ByVal CurBal as NULLABLE(of single)) as integer

Dim iReturn as integer

if NOT HistBal.HasValue  Then
    iReturn =0
else If HistBal< CurBal then 
    If (HistBal-CurBal)/HistBal <-.1 Then
        iReturn= 2 'Green arrow
    Else
        iReturn= 4 'Up yellow
    end if
Else if HistBal=CurBal then
    iReturn=0  'blank
else

    If (HistBal-CurBal)/HistBal <.1 Then
        iReturn= 3 'Dn yellow
    Else
        iReturn= 1 'red arrow
    end if
End if

return iReturn

End Function

更新：

代码 returns #ERROR:

Public Function GetIndicator(ByVal HistBal As Nullable(of single),ByVal CurBal as NULLABLE(of single)) as integer

Dim iReturn as integer

if Not HistBal.HasValue  or Not CurBal.HasValue Then
    iReturn =0
else
     iReturn= 1 
End if

return iReturn

End Function

Answer 1

Operator '<' is not defined for types 'System.Nullable(Of Single)' and 'System.Nullable(Of Single)'.

正如消息所说：显然 System.Nullable(Of T) 没有定义 < 运算符。

您已经在检查是否 HistBal.HasValue。只需检查 CurBal.HasValue 并实现逻辑，当其中一个或两个值为 null 时确定 return 的内容，然后在分支中处理 HistBal.Value 和 CurBal.Value已知两者都具有非空值。

If Not HistBal.HasValue Or Not CurBal.HasValue Then
    Return 0 'presumably return 0 when either value is null        
End If

If HistBal.Value < CurBal.Value Then 'work off the Single, not the nullable
    '...

SSRS 自定义函数和 Null 值

SSRS Custom function and Null values

vba

reporting-services

ssrs-2008-r2

ssrs-2012