Require input before update & warn if duplicate

[buckwheat]

Help I am new and stupid.

I have a form with two list boxes and 8 text boxes. I am using an append query to update a table from a push button on the form. The two list boxes are named Area and Date. I want the two list boxes to pop up a message that says " Area and Date required " and return to the form if an area or a date is not input . Also I want a warning to pop up if these two have already been updated. Below is the code I already have. I have tried this:
"If Len(Forms!main!area) = 0 Then MsgBox "You must enter an area"
I have tried ="" and = null but neither has worked. I am at a loss for the duplicate message.
Any help will be appreciated.
Buckwheat

Private Sub Command14_Enter()
DoCmd.SetWarnings (warningsoff)
On Error GoTo Err_Command14_Click
Dim stDocName As String
stDocName = "appendfrommainmenu"
DoCmd.OpenQuery stDocName, acNormal, acEdit
Forms!main!tload.Value = ""
Forms!main!tcharge.Value = ""
Forms!main!.tspa.Value = ""
Forms!main!.tda.Value = ""
Forms!main!.tunload.Value = ""
Forms!main!.ttraining.Value = ""
Forms!main!.tclerk.Value = ""
Forms!main!.twash.Value = ""
Forms!main!.tothernoprod.Value = ""
Exit_Command14_Click:
Exit Sub
Err_Command14_Click:
MsgBox Err.Description
Resume Exit_Command14_Click
End Sub

 

[bat17]

To test for Nulls use the isNull() function.

If IsNull(Forms!main!area) Then
'.....

End If

To check if the area/date combination has alredy been updated you could probably use The Dcount() function using those two fields as your criteria.

HTH

Peter

 

[buckwheat]

Peter,
Thanks for the quick response I tried the following

If IsNull(Forms!main!area) Then MsgBox "You must enter an area"

and nothing. I then tired making the default value in properties 0 and testing for that and nothing. Any other ideas? I know the table is blank where it updated everything else so I would think that the list box should return null.

 

[bat17]

try opening the debug window (ctrl-G) and entering
Print Forms!main!area

This should then give you the value that the list box is returning, this might help pin down what is happening.

Peter

 

[buckwheat]

Thanks, Please forgive some of my shrewd ways here. I am self taught and an operations manager.
It returned null and I have it somewhat working. The only problem I have is that if you click the button a second time without changing anything on the form it does nothing which might make these idiots I work with think that they have updated their numbers. Any ideas on how to make this reset or why it is not ending. I am going to play with the dcount next. Updated VB below:

If IsNull(Forms!main!area) Then MsgBox "You must enter an area"
If IsNull(Forms!main!area) Then GoTo exit_exit

On Error GoTo Err_Command14_Click

Dim stDocName As String
If Len(Forms!main!area) = 0 Then MsgBox "You must enter an area"

If IsNull(Forms!main!area) Then MsgBox "You must enter an area"
stDocName = "appendfrommainmenu"
DoCmd.OpenQuery stDocName, acNormal, acEdit

Exit_Command14_Click:
Exit Sub

Err_Command14_Click:
MsgBox Err.Description
Resume Exit_Command14_Click
exit_exit:
End Sub

 

[bat17]

I have cleaned the code up a bit and added a line to print your area value to the debug window each time it runs., that may help throw some light on what is happening

Dim stDocName As String
On Error GoTo Err_Command14_Click
Debug.Print Forms!main!area
If IsNull(Forms!main!area) Then
   MsgBox "You must enter an area"
   Exit Sub
End If

stDocName = "appendfrommainmenu"
DoCmd.OpenQuery stDocName, acNormal, acEdit
   MsgBox "Record Updated"
   
Exit_Command14_Click:
Exit Sub

Err_Command14_Click:
MsgBox Err.DESCRIPTION
Resume Exit_Command14_Click
End Sub

Peter

 

[buckwheat]

Thank you I am on the right track.