I have a form with a combo box on it where the user can select someone's name
and then hit a button to run a query that just shows records for the selected
person.  That part works just fine, the problem I have is that sometimes you
want to see everyone and I am trying to make so that if the combo box is left
empty everyone is displayed, but if you don't select someone from the combo
box the report is empty when it runs.

Here is the what I have
Form -> "frmProgChangeLogSearch"  with the following on it
    Combo box ->"cboPlantEngineer", which does have the control source empty
    Run query button -> "cmdSearchByName"

Query ->"qryChangeLogMain_Search"
    In this query I have Field "strAssignedTo" that has the criteria
[Forms]![frmProgChangeLogSearch]![cboPlantEngineer]

The cmdSearchByName button code is:

Private Sub cmdSearchByName_Click()
On Error GoTo Err_cmdSearchByName_Click

   Dim stDocName As String

   stDocName = "qryChangeLogMain_Search"
   DoCmd.OpenQuery stDocName, acNormal, acEdit

Exit_cmdSearchByName_Click:
   Exit Sub

Err_cmdSearchByName_Click:
   MsgBox Err.Description
   Resume Exit_cmdSearchByName_Click
   
End Sub

Thanks