无法在MS-Access中的子中使用函数的变量

Posted 2021-04-06

我的ms-access表单上有以下VBA代码

Option Compare Database
Option Explicit

Public Function GetUserName() As String
    Dim obj1 As Object
    Dim GetEmpID As String
    Set obj1 = CreateObject("WScript.Network")
    GetUserName = DLookup("[BAFUser]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
    GetEmpID = DLookup("[EmpID]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
    Set obj1 = Nothing
End Function

Private Sub Form_Load()
    Me.EmpName.Value = GetUserName
    Me.EmpID.Value = GetEmpID
End Sub

我可以在我的GetUserName sub中使用Load()获取值，但无法使用GetEmpID获取值。

可能的原因是什么？我该如何解决？

提前致谢。

答案

选项1：创建模块级变量，您在函数中设置（现在是子级，因为它没有返回任何值）

 Option Compare Database
 Option Explicit

 Dim UserName as String
 Dim EmpID as String

 Public Sub GetValues()
  Dim obj1 As Object

  Set obj1 = CreateObject("WScript.Network")
  UserName = DLookup("[BAFUser]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
  EmpID = DLookup("[EmpID]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
  Set obj1 = Nothing
 End Sub

Private Sub Form_Load()
    Call GetValues() 'Invoke the function to set values
    Me.EmpName.Value = UserName 'retrieve values from module level variables
    Me.EmpID.Value = EmpID
 End Sub

选项2：创建ByRef变量。

 Option Compare Database
 Option Explicit

 Public Sub GetValues(ByRef UserName as String, ByRef EmpID as String) 
  Dim obj1 As Object

  Set obj1 = CreateObject("WScript.Network")
  UserName = DLookup("[BAFUser]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
  EmpID = DLookup("[EmpID]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
  Set obj1 = Nothing
 End Sub

Private Sub Form_Load()
   Dim UserName as String
   Dim EmpID as String
    Call GetValues(UserName, EmpId) 'Invoke the function to set values of local variables.
    Me.EmpName.Value = UserName 'retrieve values from function scoped variables.
    Me.EmpID.Value = EmpID
 End Sub

警告：从内存中键入内容。可能需要进行小的修正。

另一答案

您可以随时在函数中使用ByRef。

Option Compare Database
Option Explicit

Public Function GetUserName(ByRef GetEmpID as string) as string
dim obj1 as object

Set obj1 = CreateObject("WScript.Network")

GetUserName = DLookup("[BAFUser]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")
GetEmpID = DLookup("[EmpID]", "BAF_User", "[BRID] = '" & obj1.UserName & "'")

If not obj1 is nothing then
    Set obj1 = Nothing
End If
End Function

Private Sub Form_Load()
Dim GetEmpID as string

GetEmpID = "None"

Me.EmpName.value = GetUserName(GetEmpID)
Me.EmpID.Value = GetEmpID
End Sub

ByRef传递用于将变量存储在内存中的地址。一旦传递了地址而不是仅传递了值，地址上发生的任何更改都将在整个项目中对变量进行。

有关ByVal和ByRef：http://www.cpearson.com/excel/byrefbyval.aspx的详细说明，请参阅以下网站