VBA DLookup in Loop - ms-access

Question

I've written a function to loop through an array of a custom object (C_Document). In the loop, if the document number does not already exist, it should insert a new record into the table tbl_docs. If the document does exist, it should update the appropriate record in the database.
Public Function updateDocuments(docs() As C_Document) As Double
Dim db As Object
Set db = Application.CurrentDb
Dim docIndex As Double
'Loop through all imported documents
For docIndex = 1 To UBound(docs)
Dim strSQL As String
Dim exists As Double
exists = DCount("docNo", "tbl_docs", "docNo = '" & docs(docIndex).getDocNo() & "'" > 0)
'Check if entry already exists
If (exists > 0) Then
'docNo entry already exists - update
strSQL = "UPDATE tbl_docs SET " & _
"docReviewStatus = " & docs(docIndex).getDocStatus() & "," & _
"docRev = '" & docs(docIndex).getDocReview() & "'," & _
"docDate = '" & docs(docIndex).getDocDate() & "'" & _
" WHERE (" & _
"docNo = '" & docs(docIndex).getDocNo() & "');"
Else
'docNo does not exist - insert
strSQL = "INSERT INTO tbl_docs (docNo, docReviewStatus, docRev, docDate) " & _
"SELECT '" & docs(docIndex).getDocNo() & "'" & _
"," & docs(docIndex).getDocStatus() & _
",'" & docs(docIndex).getDocReview() & "'" & _
",'" & docs(docIndex).getDocDate() & "'" & _
";"
End If
DoCmd.SetWarnings False
DoCmd.RunSQL strSQL
DoCmd.SetWarnings True
MsgBox strSQL
Next
updateDocuments = docIndex
End Function
However, when the function is called (with tbl_docs empty), it only inserts one record and the SQL string thereafter becomes the update statement.
Is there a common issue when DCount() is used in a loop? Does anyone have any experience with this logical error?

Answer 1

Your check has a slight but important error:
exists = DCount("docNo", "tbl_docs", "docNo = '" & docs(docIndex).getDocNo() & "'" > 0)
should be
exists = DCount("docNo", "tbl_docs", "docNo = '" & docs(docIndex).getDocNo() & "'") > 0
or if exists isn't bool, but simply the count, then
exists = DCount("docNo", "tbl_docs", "docNo = '" & docs(docIndex).getDocNo() & "'")

Answer 2

You can simplify and speed up this a bit using DAO, where you can do the search and update/edit in one go:
Public Function updateDocuments(docs() As C_Document) As Long
Dim db As DAO.Database
Dim rs As DAO.Recordset
Dim docIndex As Long
Dim strSQL As String
strSQL = "Select * From tbl_docs"
Set db = Application.CurrentDb
Set rs = db.OpenRecordset(strSQL)
'Loop through all imported documents
For docIndex = LBound(docs) To UBound(docs)
rs.FindFirst "docNo = '" & docs(docIndex).getDocNo() & "'"
If rs.NoMatch Then
'docNo does not exist - insert
rs.AddNew
rs!docNo.Value = docs(docIndex).getDocNo()
Else
'docNo entry already exists - update
rs.Edit
End If
rs!docReviewStatus.Value = docs(docIndex).getDocStatus()
rs!docRev.Value = docs(docIndex).getDocReview()
rs!docDate = docs(docIndex).getDocDate()
rs.Update
Next
rs.Close
updateDocuments = docIndex
End Function