选择内选择工作不正常，并显示错误

Question

我有2个表：

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

我的查询是：

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)) ; 

它返回错误

“最多一个记录可以此子查询”

返回

我试图用MAX和TOP 1像n_paytype =（选择最大（t_paytype.str_desc）设置，但表明了我错误Expr1001 Str.desc只有文本值，这可能是原因。可能是INNER JOIN可以帮助我吗？

Answer 1

看起来你不小心做了一个交叉连接。您不需要在子查询中第二次参考t_OrderPayment表 - 尝试删除（但将where子句保留为将它链接到外部查询的那个子句）。它看起来像整个子查询可以去掉，变成一个连接，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;