UNION上的SQL顺序

Question

我的查询如下：

SELECT CONVERT(VARCHAR(10),[start_of_week],103) AS WEEK_START, VisitorCount FROM mytable2
UNION 
SELECT 'Average' AS WEEK_START,AVG(VisitorCount) from mytable2
ORDER BY WEEK_START

如果我运行顶部查询，我会将所有内容排序为WEEK_START但是当我联合查询“平均”时，排序顺序会搞砸。 任何人都可以告诉我如何才能对所有WEEK_Start进行排序并将“平均值”排在最后？

更新 完整的查询是

DECLARE @From DATE = '2015-07-01'
DECLARE @To DATE = (SELECT GETDATE())
DECLARE @dt DATE = '1905-01-02';
WITH mytable as(
SELECT 

    1 as visitor,
    DATEDIFF(week, '', date) AS WeekNumber,
    DATEADD(WEEK, DATEDIFF(WEEK, @dt, [Date]), @dt) AS [start_of_week]
    FROM Showroom_perf
    Where [Date] <= @To

) , mytable2 AS ( 
Select 
[start_of_week],
COUNT(visitor) as VisitorCount
from mytable WHERE WeekNumber > '0'
GROUP BY
[start_of_week]

)
SELECT CONVERT(VARCHAR(10),[start_of_week],103) AS WEEK_START, VisitorCount, 1 as tag FROM mytable2 
UNION 
SELECT 'Average' , AVG(VisitorCount), 2 as tag  from mytable2

以下是我看到的结果：

Answer 1

更好的方法

使用ROLLUP

SELECT CASE
         WHEN Grouping(CONVERT(VARCHAR(10), start_of_week, 103)) = 1 THEN 'Average'
         ELSE CONVERT(VARCHAR(10), start_of_week, 103)
       END AS WEEK_START,
       Avg(VisitorCount)
FROM   Yourtable
GROUP  BY CONVERT(VARCHAR(10), start_of_week, 103) WITH rollup 
Order by start_of_week

• DEMO

Answer 2

只需为订单添加一个新列，并为union的每个部分赋予不同的值。由于您无法在输出中添加其他列，因此可以使用CTE稍后将其删除：

WITH temp as (
    SELECT CONVERT(VARCHAR(10),[start_of_week],103) AS WEEK_START, VisitorCount, 1 as Ord
    FROM mytable2
    UNION 
    SELECT 'Average' AS WEEK_START,AVG(VisitorCount), 2 as Ord
    from mytable2
)
SELECT WEEK_START, VisitorCount
FROM temp
ORDER BY Ord, WEEK_START

SQL Fiddle demo（简化示例）

Answer 3

在SELECT子句中创建一个虚拟列以指定Order By。 下面我为此目的使用了一个名为tag的列。

SELECT CONVERT(VARCHAR(10),[start_of_week],103) AS WEEK_START, VisitorCount FROM mytable2, 1 as tag
UNION 
SELECT 'Average' AS WEEK_START,AVG(VisitorCount),2 from mytable2
ORDER BY tag,WEEK_START

因此，第一个订单将在标记列上工作，将顶部查询结果推送到顶部，然后在UNION运算符下面的查询上进行排序。