Record with blank field not visible after using filter (1 Viewer)

i have a form with a subform and few combo box to use as a filter the data. when there is a blank field in the table it is not shown my coding for the filter is
[

Function searchcriteria()
Dim device, vlan As String
Dim task, strciteria As String


If IsNull(Me.cbodevice) Then
device = "[DEVICE NAME] like '*'"
Else
device = "[DEVICE NAME]= '" & Me.cbodevice & "'"
End If


If IsNull(Me.cbovlan) Then
vlan = "[VLAN ID] like '*'"
Else
vlan = "[VLAN ID]= '" & Me.cbovlan & "'"
End If
strcriteria = device & "And" & vlan
task = "select * from L2PORTDETAILS where " & strcriteria
Me.L2PORTDETAILS_subform.Form.RecordSource = task
Me.L2PORTDETAILS_subform.Form.Requery


End Function]

Cross posted http://www.accessforums.net/showthread.php?t=61004

The problem is if your field is NULL and not "".
Instead test to see if your search field is NOT null, then build the filter.
You'll also run into problems if the user only selects one or no options. You're building the WHERE statement and it may or may not pass arguments.

dear,
i used the same code it is not working
it is not even filtering kindly help me
thanking you again

where did you put your function? should be on the main form.

If IsNull(Me.cbodevice) Then
device = "TRUE=TRUE"
Else
device = "[DEVICE NAME]= '" & Me.cbodevice & "'"
End If


If IsNull(Me.cbovlan) Then
vlan = "TRUE=TRUE"
Else
vlan = "[VLAN ID]= '" & Me.cbovlan & "'"
End If
strcriteria = device & " And " & vlan
task = "select * from L2PORTDETAILS where " & strcriteria
Me.L2PORTDETAILS_subform.Form.RecordSource = task
' no need to requery when you change recordsource
' it is automatic
'Me.L2PORTDETAILS_subform.Form.Requery