選擇內選擇工作不正常，並顯示錯誤

Question

我有2個表：

t_orderPayment with n_id,n_order,n_paytype AND 
t_paytype with n_ID , str_desc 

我的查詢是：

SELECT t_OrderPayment.n_order , 
t_OrderPayment.n_paytype = (select t_paytype.str_desc as n_paytype from t_PayType, t_orderpayment where t_OrderPayment.n_PayType = t_PayType.n_ID) 
FROM t_OrderPayment 
WHERE (((t_OrderPayment.n_PaymentStatus)<>-7)) ; 

它返回錯誤

「最多一個記錄可以此子查詢」

返回

我試圖用MAX和TOP 1像n_paytype =（選擇最大（t_paytype.str_desc）設置，但表明了我錯誤Expr1001 Str.desc只有文本值，這可能是原因。可能是INNER JOIN可以幫助我嗎？

Answer 1

看起來你不小心做了一個交叉連接。您不需要在子查詢中第二次參考t_OrderPayment表 - 嘗試刪除（但將where子句保留爲將它鏈接到外部查詢的那個子句）。它看起來像整個子查詢可以去掉，變成一個連接，但...

SELECT t_OrderPayment.n_order, 
     t_paytype.str_desc AS n_paytype 
FROM t_OrderPayment 
     INNER JOIN t_PayType 
       ON t_OrderPayment.n_PayType = t_PayType.n_ID 
WHERE t_OrderPayment.n_PaymentStatus <> -7; 

Answer 2

SELECT t_OrderPayment.n_order， t_paytype.str_desc AS n_paytype FROM t_OrderPayment，t_PayType WHERE t_OrderPayment.n_PayType = t_PayType.n_ID AND t_OrderPayment.n_PaymentStatus <> -7;