Как указал один из предыдущих постов на SO, с ADO это проще, здесь есть пример
Пример запроса:
SELECT d.DeptID, d.Department,
ConcatADO("SELECT FName & ' ' & SName, Address FROM Persons
WHERE DeptID=" & [d].[DeptID],", "," : ") AS Who
FROM Departments AS d INNER JOIN Persons AS p ON d.DeptID = p.DeptID
GROUP BY d.DeptID, d.Department, 3;
Функция с использованием ADO
Function ConcatADO(strSQL As String, strColDelim, strRowDelim, ParamArray NameList() As Variant)
Dim rs As New ADODB.Recordset
Dim strList As String
On Error GoTo Proc_Err
If strSQL <> "" Then
rs.Open strSQL, CurrentProject.Connection
strList = rs.GetString(, , strColDelim, strRowDelim)
strList = Mid(strList, 1, Len(strList) - Len(strRowDelim))
Else
strList = Join(NameList, strColDelim)
End If
ConcatADO = strList
Exit Function
Proc_Err:
ConcatADO = "***" & UCase(Err.Description)
End Function