MS Access: outer join in a search form - ms-access

Question

I have an access database with a search form.
I have an "Object" table with amongst other things, a "name" field, and an "owner" table with a "name" field as well.
Between the two, I have a join table so I have a many-to-many relationship
An object does not necessarily have an owner.
In my search form, I have two unbound fields: "object name" and "owner name".
What I want to do:
When the user leaves both fields blank, he gets a list of all the objects (including those with no owner), and if that object has an owner it is also displayed in the list.
When the user fills something in the "object name" field, he gets a list of all the objects containing the entered substring (including those with no owner).
When the user fills something in the "owner name" field, he gets a list of all the objects where the owner name contains the entered substring (ignoring NULL owners).
What I did thus far:
I made a query with a left outer join, and a criteria on Object.name using the value of the "object name" textfield
That works fine for use case 1 and 2, but there's no owner filtering in case 3
However if I add a criteria on Owner.name based on the "owner name" textfield, case 3 works fine, but case 1 and 2 don't work anymore (making the left outer join obsolete)
How could I solve this problem?

Answer 1

It seems to me that you could use a Continuous Forms form with the following Record Source...
SELECT Objects.ObjectName, ObjectOwners.OwnerName
FROM (ObjectOwnership INNER JOIN ObjectOwners ON ObjectOwnership.OwnerID = ObjectOwners.OwnerID) INNER JOIN Objects ON Objects.ObjectID = ObjectOwnership.ObjectID
UNION ALL
SELECT Objects.ObjectName, NULL AS OwnerName
FROM ObjectOwnership RIGHT JOIN Objects ON Objects.ObjectID = ObjectOwnership.ObjectID
WHERE ObjectOwnership.ObjectID IS NULL
ORDER BY 1, 2;
...and then put a couple of text boxes and a "Filter" command button in the form header to update the forms .Filter property to filter the records as desired, like this:
Private Sub cmdFilter_Click()
Dim sFilter As String
If IsNull(Me.txtObjectFilter.Value) And IsNull(Me.txtOwnerFilter.Value) Then
Me.FilterOn = False
Else
If IsNull(Me.txtObjectFilter.Value) Then
sFilter = ""
Else
sFilter = "ObjectName LIKE ""*" & Me.txtObjectFilter.Value & "*"""
End If
If Not IsNull(Me.txtOwnerFilter.Value) Then
If Len(sFilter) > 0 Then
sFilter = sFilter & " AND "
End If
sFilter = sFilter & "Ownername LIKE ""*" & Me.txtOwnerFilter.Value & "*"""
End If
Me.Filter = sFilter
Me.FilterOn = True
End If
End Sub
When the form opens it shows all records...
...and then we can filter by object...
...or by owner...
...or both, for that matter.
Edit
A similar technique for Subforms would be to save the query above as [ObjectOwner_base_query] and specify that as the Record Source of the Subform, then change the VBA code very slightly, to
Private Sub cmdFilter_Click()
Dim sFilter As String, sSQL As String
sFilter = ""
If Not IsNull(Me.txtObjectFilter.Value) Then
sFilter = "ObjectName LIKE ""*" & Me.txtObjectFilter.Value & "*"""
End If
If Not IsNull(Me.txtOwnerFilter.Value) Then
If Len(sFilter) > 0 Then
sFilter = sFilter & " AND "
End If
sFilter = sFilter & "Ownername LIKE ""*" & Me.txtOwnerFilter.Value & "*"""
End If
sSQL = "SELECT * FROM ObjectOwner_base_query"
If Len(sFilter) > 0 Then
sSQL = sSQL & " WHERE " & sFilter
End If
Me.RecordSource = sSQL
End Sub
(It appears that modifying the .Filter property of a subform can cause Access to act strangely; updating the .RecordSource property seems to produce better results.)