Validating a textbox entry if duplicate display error message microsoft access - vba

Question

i have searched around and cant find an answer, so i am using Microsoft Access Office 2019 and cant seem to validate my textbox for a duplicate entry. The user will add a record and enter a short text primary key (which in this case is the new employee's ID) Field - [EMPID] in the [EMPDETAILS] table. The below code has worked for validating my Autonumber primary key but doesnt seem to work for a custom short text primary key and i am getting this error
"The expression you entered as a query parameter produced this error :
'VS123'
<= this is the Employee ID which is a custom short text primary key :
Private Sub unqidd_BeforeUpdate(Cancel As Integer)
On Error GoTo Err_Handler
Dim strMessage As String
'PartNum is the name of a textbox that contains the primary key, the rest are text to display.
strMessage = "Employee ID" & Me!unqidd & " already exists."
' confirm that part number doesn't already exist.
If (DLookup("[empid]", "[empdetails]", "[empID] = " & Forms![driverdetails]![unqidd])) Then
MsgBox strMessage, vbInformation, "Invalid Operation"
Cancel = True
End If
Exit_Here:
Exit Sub
Err_Handler:
MsgBox Err.Description
Resume Exit_Here
End Sub

Answer 1

Since you are trying to add a string into [empID] I am going to assume it is a string field, in which case you need to include quotes:
If (DLookup("[empid]", "[empdetails]", "[empID] = '" & Forms![driverdetails]![unqidd] & "'")) Then

Answer 2

The solution is as below :
1) Create an unbound textbox (Text1616) and set its control source as
=DLookUp("[empid]","[empdetails]","[empID] = '" & [Forms]![Driverdetails]![unqidd] & "'")
2) The textbox (Unqidd) that will need to be validated, on its beforeupdate property set the event procedure code as below :
Private Sub unqidd_BeforeUpdate(Cancel As Integer)
On Error GoTo Err_Handler
Dim strMessage As String
'PartNum is the name of a textbox that contains the primary key, the rest are text to
display.
strMessage = "Employee ID" & Me!unqidd & " already exists."
' confirm that part number doesn't already exist.
If Me.unqidd.Value = Me.Text1616 Then
MsgBox strMessage, vbInformation, "Invalid Operation"
Cancel = True
End If
Exit_Here:
Exit Sub
Err_Handler:
MsgBox Err.Description
Resume Exit_Here
End Sub
'References :
'Table Name : empdetails
'Table primary key : empid (Short text)
'Form Name : Driverdetails
'Textbox 1 : unqidd (no formats, control source : empid)
'Textbox 2 : Text1616 (Unbound Textbox)