Question

给出以下Select Statement

String cmpquery = "SELECT cwfour.ord_number, cwfour.ord_status,  
orderheader.ord_status 
FROM live.dbo.cwfour cwfour, live.dbo.orderheader orderheader
WHERE ((cwfour.ord_number = orderheader.ord_hdrnumber AND NOT 
cwfour.ord_status='CAN')) or ((cwfour.ord_number = orderheader.ord_hdrnumber 
AND NOT cwfour.ord_status='CMP'))"

结果集显示文件中的所有订单，但我只要求那些不是CAN或CMP，取消或完成的订单。我的where子句中缺少什么？

Answer 1

您正在查询状态为“无法”的行。或者不是CMP＆＃39;它将返回所有行，因为＆＃39; CAN＆＃39;问题＆＃39; CMP＆＃39;反之亦然。相反，您应该查询行也不是。 E.g：

SELECT cwfour.ord_number, cwfour.ord_status, orderheader.ord_status
FROM   live.dbo.cwfour cwfour, live.dbo.orderheader orderheader
WHERE  cwfour.ord_number = orderheader.ord_hdrnumber AND
       cwfour.ord_status NOT IN ('CAN', 'CMP')

值得注意的是，隐式连接（在from子句中列出多个表）已经被认为已经过时很长时间了。相反，建议使用显式连接：

SELECT cwfour.ord_number, cwfour.ord_status, orderheader.ord_status
FROM   live.dbo.cwfour cwfour
JOIN   live.dbo.orderheader orderheader ON 
       cwfour.ord_number = orderheader.ord_hdrnumber
WHERE  cwfour.ord_status NOT IN ('CAN', 'CMP')

Answer 2

逻辑！

你的条件是：

(cwfour.ord_number = orderheader.ord_hdrnumber AND NOT cwfour.ord_status='CAN')
OR
(cwfour.ord_number = orderheader.ord_hdrnumber AND NOT cwfour.ord_status='CMP')

A AND !B
OR
A AND !C

哪个是

A & (!B | !C)

简单地说：A & (almost anything);）

Java选择语句结果问题

2 个答案: