Checking if record exists using DLookup (With Multiple Criteria) - ms-access

Question

Im trying to create a function in my VBA where if the record they are trying to insert already exists however it returns a type mismatch.
EventCombo is a integer
MedalCombo is string
Private Sub MyCombo_BeforeUpdate(Cancel As Integer)
If Not IsNull(DLookup("RacerID", "Medals", "RaceID = " + EventCombo.Value _
+ " AND Medal = '" + MedalCombo.Value + "'" )) Then
MsgBox "Record Exists"
End If.
End Sub
What this does (or is supposed to do) is make sure no one else has the same medal in the same race.
What am I doing wrong?

Answer 1

With combo boxes in Access, you need to make sure that .value is really what you want. Often the first column is hidden which is .value while what is visible on the drop down box is not .value. When using a combo box to eliminate confusion I use the .columns property.
Also, to make sure the result from the combo box is a number and not text (as you did not use quotes in your example) I used the val() function to convert the combobox data to a number. If it already is a number, this will have no effect. Otherwise, if it is a digit stored as a string, it will convert it to a number. This might not be strictly necessary but it eliminates another possible problem. If the combobox column has a value which is some text which cannot convert to a number it will return 0 which you can test for in your code.
I cleaned up your code a bit with the following
I replaced the + with & like Remou said
changed .value to .columns(0). If the column you are looking for is not the first one, change 0 to the appropriate value
value() function
removed line continuation _. (Personal preference, feel free to ignore)
Private Sub MyCombo_BeforeUpdate(Cancel As Integer)
If Not IsNull(DLookup("RacerID", "Medals", "RaceID = " & Val(EventCombo.Columns(0)) & " AND Medal = '" & MedalCombo.Columns(0) & "'")) Then
MsgBox "Record Exists"
End If
End Sub