具有 2 个参数和嵌套的函数

Question

包含 3000 条记录和 21 列字段的表

我需要使用 2 个列字段（Field2 和 Field3）循环遍历记录，其中有一个空值来生成一个新列字段（Field4） 我从下面的这个函数开始，但我被卡住了，因为 case select 不能接受 null- 或者我可能需要使用我不擅长的嵌套 iif。

样本表

Name(Field1)  Parts(Field2)   Categories(Field3)  New Field(Field4)
1              A1              R1                 Inventory
2              A1              Null               Inventory
3              B1              R1                 Processing
4              B1              R4                 Processing
5              B1              Null               Unknown 
6              Null            Null               Unknown

我的功能：

Function MachineCheck(Field2, Field3) As String

Dim newValue As String

Select Case (Field2)
     Case "A1":
        Select Case (Field3)
            Case "R1"
                newValue = "Inventory"
            Case Is null
                newValue = "Inventory"
            Case "R1"
                newValue = "Inventory"
            Case “ “
                newValue = "Inventory"

       Select Case (Field2)
         Case “B1”
End Select

MachineCheck = newValue
End Function

感谢您的帮助！

Answer 1

我建议这样写查询：

SELECT Field1 AS [Name], Field2 AS Parts, Field3 AS Categories, 
      SWITCH( Trim(Field3) & Trim(Field4) = "A1", "Inventory",
              Trim(Field3) & Trim(Field4) = "A1R1", "Inventory", 
              Trim(Field3) & Trim(Field4) = "B1", "Unknown",
              Trim(Field3) & Trim(Field4) = "B1R1", "Processing",
              Trim(Field3) & Trim(Field4) = "", "Unknown") As [Status]
FROM YourTable;

欲了解更多信息，请参阅：What is the equivalent of Select Case in Access SQL?