VBA Query based on multiple "multiple select list boxes" in Access when not selecting an item from one of the multiple select boxes - sql

Question

I have the following vba that creates a query in a test Access database. I have two multiple select list boxes. The issue is, i want to be able to select multiple items from "Me![State]" and none from "Me![Animal]" and be able to run the query. However, this is not possible as the query language is not set up to handle that. It makes me select something from "Me![Animal]".
How do i revise the vba below to allow me to query on both multiple selection list boxes if one of the multiple list boxes does not have anything selected or if both have selections in them?
Private Sub Command6_Click()
Dim Q As QueryDef, DB As Database
Dim Criteria As String
Dim ctl As Control
Dim Itm As Variant
Dim ctl2 As Control
Dim ctl3 As Control
' Build a list of the selections.
Set ctl = Me![Animal]
For Each Itm In ctl.ItemsSelected
If Len(Criteria) = 0 Then
Criteria = Chr(34) & ctl.ItemData(Itm) & Chr(34)
Else
Criteria = Criteria & "," & Chr(34) & ctl.ItemData(Itm) _
& Chr(34)
End If
Next Itm
If Len(Criteria) = 0 Then
Itm = MsgBox("You must select one or more items in the" & _
" list box!", 0, "No Selection Made")
Exit Sub
End If
Set ctl2 = Me![State]
For Each Itm In ctl2.ItemsSelected
If Len(Criteria2) = 0 Then
Criteria2 = Chr(34) & ctl2.ItemData(Itm) & Chr(34)
Else
Criteria2 = Criteria2 & "," & Chr(34) & ctl2.ItemData(Itm) _
& Chr(34)
End If
Next Itm
If Len(Criteria2) = 0 Then
Itm = MsgBox("You must select one or more items in the" & _
" list box!", 0, "No Selection Made")
Exit Sub
End If
' Modify the Query.
Set DB = CurrentDb()
Set Q = DB.QueryDefs("animalquery")
' Modify the Query.
Set DB = CurrentDb()
Set Q = DB.QueryDefs("animalquery")
Q.SQL = "Select * From [table1] Where [table1].[type] In (" & "'Animal'" & _
")" & " and [table1].[animal] in (" & Criteria & _
")" & " and [table1].[state] in (" & Criteria2 & _
")" & ";"
Q.Close
' Run the query.
DoCmd.OpenQuery "animalquery"
End Sub

Answer 1

EDIT - Fix comparison as per comment
You can do this with a simple check of your Criteria vaiables.
You already do the the length check - just use it later on when you build the dynamic SQL.
I added a strSQL variable to make it easier to track what's happening. And adjusted the error message to allow one or other criteria being empty
Private Sub Command6_Click()
Dim Q As QueryDef
Dim DB As Database
Dim Criteria As String
Dim ctl As Control
Dim Itm As Variant
Dim ctl2 As Control
Dim ctl3 As Control
' Use for dynamic SQL statement'
Dim strSQL As String
Set ctl = Me![Animal]
For Each Itm In ctl.ItemsSelected
If Len(Criteria) = 0 Then
Criteria = Chr(34) & ctl.ItemData(Itm) & Chr(34)
Else
Criteria = Criteria & "," & Chr(34) & ctl.ItemData(Itm) & Chr(34)
End If
Next Itm
Set ctl2 = Me![State]
For Each Itm In ctl2.ItemsSelected
If Len(Criteria2) = 0 Then
Criteria2 = Chr(34) & ctl2.ItemData(Itm) & Chr(34)
Else
Criteria2 = Criteria2 & "," & Chr(34) & ctl2.ItemData(Itm) & Chr(34)
End If
Next Itm
If (Len(Criteria) = 0) And (Len(Criteria2) = 0) Then
Itm = MsgBox("You must select one or more items from one of the list boxes!", 0, "No Selection Made")
Exit Sub
End If
' Modify the Query.
Set DB = CurrentDb()
Set Q = DB.QueryDefs("animalquery")
' Modify the Query.
Set DB = CurrentDb()
Set Q = DB.QueryDefs("animalquery")
strSQL = "Select * From [table1] Where [table1].[type] In (" & "'Animal')"
If (Len(Criteria) <> 0) Then ' Append Animal Criteria
strSQL = strSQL & " AND [table1].[animal] IN (" & Criteria & ")"
End If
If (Len(Criteria2) <> 0) Then ' Append State Criteria
strSQL = strSQL & " AND [table1].[state] IN (" & Criteria2 & ")"
End If
Q.SQL = strSQL
Q.Close
' Run the query.
DoCmd.OpenQuery "animalquery"
End Sub