如何让整数在 combox.value 中接收 null？

Question

   Private Sub SubmitButton1_Click()
 Dim month As Integer
 Dim fromm As Integer
 Dim too As Integer


month = monthComboBox.Value
fromm = fromComboBox.Value
too = toComboBox.Value
'''''''''''''''''''''''''''''''''''''''
'''''''''''''
'''''''''''''


Dim sSQLQry As String
Dim ReturnArray

Dim Conn As New ADODB.Connection
Dim mrs As New ADODB.Recordset

Dim DBPath As String, sconnect As String



DBPath = ThisWorkbook.FullName



sconnect = "Provider=MSDASQL.1;DSN=Excel Files;DBQ=" & DBPath & ";HDR=Yes';"

Conn.Open sconnect

If (IsNull(fromComboBox.Value)) And (IsNull(toComboBox.Value)) = True Then
      sSQLSting = "SELECT  officer  From  [big$]  where officer is not null and officer <> '' and officer <> ' ' and Month between " & fromm & " and " & too & " group by officer "
  Set rs = Conn.Execute(sSQLSting)
  Else
  sSQLSting = "SELECT  officer  From  [big$]  where officer is not null and officer <> '' and officer <> ' ' and Month= " & month & " group by officer " ' 


    Set rs = Conn.Execute(sSQLSting)
    End If

enter image 案例： 这里有 3 个组合框。用户应该 select "by month" 或“按月”。这 3 个组合框选项里面都是相同的 .additem 1 .additem 2 .additem 3 ... .additem 12

我用If (IsNull(fromComboBox.Value)) And (IsNull(toComboBox.Value)) = True Then A SQL A else-SQL-B

现在，它在 month = monthComboBox.Value fromm = fromComboBox.Value too = toComboBox.Value

上显示数据类型不匹配错误

在我看来，由于用户应该输入 "by month" 或 "by month period" ，一个 combobox.value 应该是 "" （字符串数据类型）。因此，它发生数据类型不匹配。（变量存储combobox.value是整数）

如何解决？顺便说一句，If (IsNull(fromComboBox.Value)) And (IsNull(toComboBox.Value)) = True Then A SQL A else-SQL-B，这个条件似乎并不完全有效。有什么想法吗？

更新

1)我使用这些代码解决了 null 不能传递整数的问题。不知道它是否有效。

 Dim month As Integer
     Dim fromm As Integer
     Dim too As Integer

If IsNumeric(monthComboBox.Value) Then
month = monthComboBox.Value
Else
month = 0
End If
''''
If IsNumeric(fromComboBox.Value) Then
fromm = fromComboBox.Value
Else
fromm = 0
End If
'''''
If IsNumeric(toComboBox.Value) Then
too = toComboBox.Value
Else
too = 0
End If

2) if 条件无效。结果："Else statement " 对 monthcombobox 有效； "Then statement no effect . In other words , only "按月组合框工作。"by month period"

没有输出

If ((IsEmpty(fromComboBox.Value) Or IsNull(fromComboBox.Value)) = True And (IsEmpty(toComboBox.Value)) Or IsNull(toComboBox.Value)) = True Then 
  sSQLSting = "SELECT  officer  From  [big$]  where officer is not null and officer <> '' and officer <> ' ' and Month between " & fromm & " and " & too & " group by officer "
  Set rs = Conn.Execute(sSQLSting)
  Else
  sSQLSting = "SELECT  officer  From  [big$]  where officer is not null and officer <> '' and officer <> ' ' and Month= " & month & " group by officer " ' 


    Set rs = Conn.Execute(sSQLSting)
    End If

Answer 1

要检查 ComboBox 对象值选择，请使用其 ListIndex 属性

此外，您的逻辑需要增强，让您捕捉并使用任何 "valid" 用户选择并拒绝任何无效选择

最后你的代码有一些未声明的 and/or 未使用的变量：你最好在你的模块的最顶部使用 Option Explicit 并强制你声明所有变量：以这个小的代价额外的工作，您将获得对代码的更多控制，并使后续的调试和维护工作更快

对于上面的所有代码，请使用以下代码

Option Explicit

Private Sub SubmitButton1_Click()

Dim month As Integer
Dim fromm As Integer
Dim too As Integer
Dim sSQLString As String

With Me
    Select Case True
        Case .monthComboBox.ListIndex <> -1 '<--| a valid "by month" choice has been made, then use it to build consequent SQL string
            month = monthComboBox.value
            sSQLString = "SELECT  officer  From  [big$]  where officer is not null and officer <> '' and officer <> ' ' and Month= " & month & " group by officer "

        Case .fromComboBox.ListIndex <> -1 And .toComboBox.ListIndex <> -1 '<--| a valid "by month period" choice has been made, then use it to build consequent SQL string
            fromm = fromComboBox.value
            too = toComboBox.value
            sSQLString = "SELECT  officer  From  [big$]  where officer is not null and officer <> '' and officer <> ' ' and Month between " & fromm & " and " & too & " group by officer "

        Case Else '<--| no vaild "month" choice hase been made, then inform the user about it
            MsgBox "invalid months data choice!", vbInformation + vbExclamation
    End Select
End With

If sSQLString = "" Then Exit Sub '<--| exit if no SQL string has been initilalized

Dim DBPath As String, sconnect As String
Dim Conn As New ADODB.Connection
Dim rs As New ADODB.Recordset

DBPath = ThisWorkbook.FullName
sconnect = "Provider=MSDASQL.1;DSN=Excel Files;DBQ=" & DBPath & ";HDR=Yes';"
Conn.Open sconnect
Set rs = Conn.Execute(sSQLString)

'Dim sSQLQry As String '<--| are you actually using them?
'Dim ReturnArray '<--| are you actually using them?


End Sub

如何让整数在 combox.value 中接收 null？

How to allow integer receive null in combox.value?

sql

excel

vba

ado

更新