Question

所有人都给出了正确的结果，而工会给出了错误的结果。

SELECT * 
  FROM (SELECT TOP 20 * 
          FROM noble_win 
         WHERE [YEAR ] = 1970 
           AND [SUBJECT   ]  NOT IN ('Economics', 'Chemistry') 
        ORDER BY [SUBJECT   ],[WINNER                ]) AS A
UNION
SELECT * 
  FROM (SELECT TOP 20 * 
          FROM noble_win 
         WHERE [YEAR ]=1970 
           AND [SUBJECT   ] IN ('Economics', 'Chemistry') 
        ORDER BY [SUBJECT   ],[WINNER                ]) AS B

此查询先给出Chemistry和Economics行，然后给出Economics和Chemistry以外的行。但是，我首先要使用Economics和Chemistry以外的行。我不知道为什么会给出错误的结果。

Answer 1

ORDER BY必须在最外面的查询级别应用：

select  * from 
(select top 20 *,1 AS ord from noble_win 
 where [YEAR ]=1970 and [SUBJECT   ]  NOT IN ('Economics', 'Chemistry')
 order by [SUBJECT   ],[WINNER                ]
)  as A
union 
select * from 
(select top 20 *, 2 AS ord from noble_win 
 where [YEAR ]=1970 and [SUBJECT   ] IN ('Economics', 'Chemistry')
 order by [SUBJECT   ],[WINNER                ]
) as B
order by ord, [SUBJECT   ],[WINNER                ])

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Answer 2

您可以使用CASE语句进行条件排序：

<Sidebar
  sidebar={<b>Sidebar content</b>}
  open={this.state.sidebarOpen}
  onSetOpen={this.onSetSidebarOpen}
  styles={{ sidebar: { background: "white" } }}
>
   <button onClick={() => this.onSetSidebarOpen(true)}>  //button as children
      Open sidebar
   </button>
</Sidebar>

Answer 3

如果使用union / union all，则order by必须位于最外面的选择上。但是，您不需要它们。您可以只使用表达式和窗口函数：

select nw.* 
from (select nw.*,
             row_number() over (partition by year,
                                             (case when [SUBJECT   ] in ('Economics', 'Chemistry') then 1 else 2 end)
                                order by [SUBJECT   ], [WINNER                ])
                               ) as seqnum
      from noble_win nw
     ) nw
where seqnum <= 20
order by (case when [SUBJECT   ] in ('Economics', 'Chemistry') then 1 else 2 end) desc,
         [WINNER                ]);

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3 个答案: