我該如何改進MS Access中的SQL查詢VBA

Question

如何改進我的查詢，以便只應選擇那些尚未在Pasenger_Detail表中選擇的記錄。

Private Sub BR_ID_LostFocus() 
    Dim s As String 

    s = "Select seat_no.seat_no" & _ 
     " FROM Seat_No" & _ 
     " Where seat_no.seat_no <= " & _ 
     " (select br_info.Seats_Reserved from br_info where " & _ 
     " Br_info.br_id=forms!pasenger_detail!br_id);" 

    Me.Seat_No.RowSource = s 
    Me.Seat_No.Requery 
End Sub 

Answer 1

您可以在下面的WHERE子句中使用Not In。如果它沒有在子查詢中找到座位，那麼它將在結果中列出seat_no。

SELECT Seat_No.seat_no 
FROM Seat_No 
WHERE Seat_No.seat_no <= 
(
    SELECT br_info.Seats_Reserved 
    FROM br_info 
    WHERE br_info.br_id = forms!pasenger_detail!br_id 
) 
AND Seat_No.seat_no NOT IN 
(
    SELECT pasenger_detail.seat_no 
    FROM pasenger_detail 
)