如何通过多个联合语句的结果进行排序？

Question

我不能使用公用表表达式：

WITH    cte
          AS (SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB1].[dbo].[ProcessingStations]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB2].[dbo].[ProcessingStations]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB3].[dbo].[ProcessingStations]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB4].[dbo].[ProcessingStations]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB5].[dbo].[ProcessingStations]
              ORDER BY  [StationID]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB6].[dbo].[ProcessingStations]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB7].[dbo].[ProcessingStations]
              UNION ALL
              SELECT    [StationID],
                        [LastDistribution]
              FROM      [DB8].[dbo].[ProcessingStations])
    SELECT  *
    FROM    cte
    ORDER BY StationID

我将如何做到这一点？

Answer 1

只需将ORDER BY放在SELECT ... FROM ... UNION ALL语句链的末尾：

SELECT    [StationID],
          [LastDistribution]
          FROM      [DB1].[dbo].[ProcessingStations]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB2].[dbo].[ProcessingStations]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB3].[dbo].[ProcessingStations]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB4].[dbo].[ProcessingStations]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB5].[dbo].[ProcessingStations]
          ORDER BY  [StationID]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB6].[dbo].[ProcessingStations]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB7].[dbo].[ProcessingStations]
          UNION ALL
          SELECT    [StationID],
                    [LastDistribution]
          FROM      [DB8].[dbo].[ProcessingStations]
ORDER BY StationID

以下是我在SSMS中做的一个简单示例：

DECLARE @a table (x int)
DECLARE @b table (x int)
DECLARE @c table (x int)

insert into @a values (5)
insert into @a values (4)
insert into @a values (3)

insert into @b values (0)
insert into @b values (1)
insert into @b values (2)

insert into @c values (0)
insert into @c values (1)
insert into @c values (2)

select * from @a
union all
select * from @b
union all
select * from @c
order by x

这是输出：

  x
-----
  0
  0
  1
  1
  2
  2
  3
  4
  5

正如您所看到的，即使SELECT * FROM @a排在第一位，它仍将最后一个放在结果集中

Answer 2

为什么不能使用CTE？无论如何，您仍然可以使用派生表执行相同的操作：

SELECT *
FROM (  SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB1].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB2].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB3].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB4].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB5].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB6].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB7].[dbo].[ProcessingStations]
        UNION ALL
        SELECT    [StationID],
                  [LastDistribution]
        FROM      [DB8].[dbo].[ProcessingStations]) A
ORDER BY StationID

Answer 3

请参阅fiddle，只需将ORDER BY放在最后一组即可“联合”。它可以在没有CTE开销的情况下实现相同的结果。

订单将影响整个统一集。

SELECT
        [StationID],
        [LastDistribution]
    FROM 
        [dbo].[ProcessingStations]
UNION ALL
SELECT
        [StationID],
        [LastDistribution]
    FROM 
        [dbo].[ProcessingStations]
UNION ALL
SELECT
        [StationID],
        [LastDistribution]
    FROM 
        [dbo].[ProcessingStations]
    ORDER BY
        [StationID]