Sql 在联合查询中对别名列排序

我有一个多次使用联合的SQL查询，在其中我创建了一个名为“Category”的别名列。当我在alias列上尝试一个简单的order by时，效果很好。但是，“我的别名”列中的数据有数字，它们的顺序是1,10,11，而不是1,2,3等

当我尝试将order by更改为order by len时，我突然出现两个错误。。。1表示“类别”列不存在，另一列表示“如果语句包含UNION、INTERSECT或EXCEPT运算符，则ORDER BY items必须出现在选择列表中”。当我尝试将其转换为INT时，也同样适用

查询的精简版本如下所示

SELECT 'Category 1' as Category, category1Score as categoryScore
from table1
WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' and 
'10/10/2019'
UNION
SELECT 'Category 2' as Category, category2Score as categoryScore
from table1
WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' and 
'10/10/2019'
UNION
SELECT 'Category 10' as Category, category10Score as categoryScore
from table1
WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' and 
'10/10/2019'

例如，我想按类别1、类别2、类别10进行订购。

您可以在下面进行尝试-

select Category,  categoryScore from
(
SELECT 'Category 1' as Category, category1Score as categoryScore,1 as ord
from table1
WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' and 
'10/10/2019'
UNION
SELECT 'Category 2' as Category, category2Score as categoryScore,2
from table1
WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' and 
'10/10/2019'
UNION
SELECT 'Category 10' as Category, category10Score as categoryScore,3
from table1
WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' and 
'10/10/2019'
)A order by ord

---

子查询，然后按

类别

列排序：

SELECT Category, CategoryScore
FROM
(
    SELECT 'Category 1' AS Category, category1Score AS categoryScore, 1 AS pos
    FROM table1
    WHERE lineNumber = 'Reflow 2' AND dateOfAudit BETWEEN '01/10/2019' AND '10/10/2019'
    UNION ALL
    SELECT 'Category 2', Category2Score, 2
    FROM table1
    WHERE lineNumber = 'Reflow 2' AND dateOfAudit BETWEEN '01/10/2019' AND '10/10/2019'
    UNION ALL
    SELECT 'Category 10', category10Score, 3
    FROM table1
    WHERE lineNumber = 'Reflow 2' AND dateOfAudit BETWEEN '01/10/2019' AND '10/10/2019'
) t
ORDER BY
    pos;

注:

我在这里使用

UNION ALL

而不是

UNION

，因为您的意图很可能是不删除重复项。还请注意，您只需要在联合的第一个查询中使用别名。事实上，后续别名将被忽略

最后，我选择引入一个新的计算列，名为

pos

，它为联合中的每个查询编码所需的顺序。虽然我们只能依赖于

类别

，但如果您的查询可能会发生更改，则以后按类别排序可能会出现意外行为，因为它是文本，而不是纯数字。

请尝试下面的查询

 with CTE as 
(
    SELECT 'Category 1' as Category, category1Score as categoryScore
    from table1
    WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' 
and '10/10/2019'
    UNION
    SELECT 'Category 2' as Category, category2Score as categoryScore
    from table1
    WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' 
    and '10/10/2019'
    UNION
    SELECT 'Category 10' as Category, category10Score as categoryScore
    from table1
    WHERE lineNumber = 'Reflow 2' and dateOfAudit between '01/10/2019' 
    and '10/10/2019'
) select Category,categoryScore from CTE
ORDER BY
    Category ASC

---

为什么要使用

union

进行外部查询

select c.Category,
       (case ord
            when 1 then category1Score
            when 2 then category2Score
            when 3 then category3Score
            when 4 then category4Score
            when 5 then category5Score
            when 6 then category6Score
            when 7 then category7Score
            when 8 then category8Score
            when 9 then category9Score
            when 10 then category10Score
            when 1 then category1Score
        end) as categoryScore
from table1 t1 cross join
     (select 'Category 1' as category, 1 as ord union all
      select 'Category 2', 2 as ord union all
      select 'Category 3', 3 as ord union all
      select 'Category 4', 4 as ord union all
      select 'Category 5', 5 as ord union all
      select 'Category 6', 6 as ord union all
      select 'Category 7', 7 as ord union all
      select 'Category 8', 8 as ord union all
      select 'Category 9', 9 as ord union all
      select 'Category 10', 10 as ord
     ) c
where t.lineNumber = 'Reflow 2' and
      t.dateOfAudit between '2019-10-01' and '2019-10-10'
order by c.ord;

---

通过将表上的筛选条件仅放在一个位置，这样可以减少编写查询时的错误范围。

可能会重复使用正在使用的数据库标记问题。