Question

I’m not an SQL Expert. Maybe what I’m trying to do here isn’t even possible.

I’m trying to get an updateable recordset that includes a field that is the result of an aggregate function.

I’m looking for something like this:

SELECT Contact.*, Count(OrderID) as CountOfOrders
FROM Contact INNER JOIN Order ON Order.ContactID = Contact.ContactID
WHERE ContactID = 1

Answer 1

When using the MSDataShape OLE DE provider and the OLE DB provider for Jet (or ACE) then it is indeed possible to create an updateable ADO recordset and APPEND a computed column based on a set function such as COUNT(). The resulting SQL-esque code would look more like this:

 SHAPE  {SELECT ContactID, ContactName FROM Contact} 
APPEND ({SELECT ContactID, OrderID FROM Orders} 
         RELATE ContactID TO ContactID
       ) As rsDetails, COUNT(rsDetails.OrderID) AS CountOfOrder

Here’s a brief ‘proof of concept’: paste the following into any VBA module (e.g. use Excel), no references required, creates a new .mdb in your temp directory, creates the tables with data, to prove the recordset is updateable the ContactName value is changed and the recordset reopened to show it has indeed changed:

Sub ShapeAppendCount()

  On Error Resume Next
  Kill Environ$("temp") & "\DropMe.mdb"
  On Error GoTo 0

  Dim cat
  Set cat = CreateObject("ADOX.Catalog")
  With cat
    .Create _
        "Provider=Microsoft.Jet.OLEDB.4.0;" & _
        "Data Source=" & _
        Environ$("temp") & "\DropMe.mdb"

    Dim jeng
    Set jeng = CreateObject("JRO.JetEngine")
    jeng.RefreshCache .ActiveConnection

    Set .ActiveConnection = Nothing
  End With

  Dim con
  Set con = CreateObject("ADODB.Connection")
  With con
    .ConnectionString = _
        "Provider=MSDataShape;" & _
        "Data Provider=Microsoft.Jet.OLEDB.4.0;" & _
        "Data Source=" & _
        Environ$("temp") & "\DropMe.mdb"
    .CursorLocation = 3
    .Open

    .Execute _
    "CREATE TABLE Contact (" & _
    "ContactID INTEGER NOT NULL UNIQUE, " & _
    "ContactName VARCHAR(20) NOT NULL);"

    .Execute _
    "CREATE TABLE Orders (" & _
    "ContactID INTEGER NOT NULL REFERENCES Contact (ContactID), " & _
    "OrderID INTEGER NOT NULL UNIQUE);"

    .Execute _
    "INSERT INTO Contact (ContactID, ContactName)" & _
    " VALUES (1, 'OneDayWhen');"

    .Execute _
    "INSERT INTO Orders (ContactID, OrderID)" & _
    " VALUES (1, 1);"

    .Execute _
    "INSERT INTO Orders (ContactID, OrderID)" & _
    " VALUES (1, 2);"

    Dim rs
    Set rs = CreateObject("ADODB.Recordset")
    With rs
      .CursorType = 2  ' adOpenDynamic
      .LockType = 4  ' adLockBatchOptimistic

      .Source = _
      " SHAPE {SELECT ContactID, ContactName FROM Contact} " & _
      "APPEND ({SELECT ContactID, OrderID FROM Orders} " & _
      "RELATE ContactID TO ContactID) As rsDetails, " & _
      " COUNT(rsDetails.OrderID) AS CountOfOrder"

      Set .ActiveConnection = con
      .Open

      .Fields("ContactName").Value = "Pink Cat"

      .UpdateBatch

      MsgBox .GetString
      .Close
    End With

    With rs
      .Source = _
      "SELECT ContactID, ContactName FROM Contact"

      Set .ActiveConnection = con
      .Open

      MsgBox .GetString
      .Close

    End With
  End With
End Sub