因此，我能够修改Gustav的逻辑并使它适合我的项目。我将父结果放在定界符“;”之间。这样可以更轻松地在查询中查找特定ContentID的后代。此外，由于某些ContentID是树的开头，因此我不得不处理父列中的Null值。

Public Function GetParentIDs(ByVal lContentID As Long) As String
    Static dbs As DAO.Database
    Static tbl As DAO.TableDef
    Static rst As DAO.Recordset
    Dim strParents As String

    If dbs Is Nothing Then
        ' For testing only.
        ' Replace with OpenDatabase of backend database file.
        Set dbs = CurrentDb
        Set tbl = dbs.TableDefs("tbContentList")
        Set rst = dbs.OpenRecordset(tbl.Name, dbOpenTable)
    End If

    With rst
        .Index = "PrimaryKey"
        Do While lContentID > 0
            .Seek "=", lContentID
            If Not .NoMatch Then
                lContentID = Nz(!ParentID.Value, 0)
                If lContentID > 0 Then
                    strParents = ";" & CStr(lContentID) & strParents
                Else
                    Exit Do
                End If
            Else
                Exit Do
            End If
        Loop
        ' Leave recordset open.
        ' .Close
    End With

    '  Don't terminate static objects.
    '  Set rst = Nothing
    '  Set tbl = Nothing
    '  Set dbs = Nothing

    'Return value
    If strParents = "" Then
        GetParentIDs = ""
    Else
        GetParentIDs = strParents & ";"
    End If
End Function

从特定ContentID获取所有后代的查询。如果在此示例中为3，则可以将其更改为另一个值。

SELECT tbContentList.[ContentID], tbContentList.[ParentID], tbContentList.[Item], GetParentIDs([ContentID]) AS Parents
FROM tbContentList
WHERE (((GetParentIDs([ContentID])) Like '*;3;*'));

感谢你的帮助，使我朝着正确的方向前进。