从单行返回多行

Question

这可能是不可能的，但我想我会把它扔在这里：

给定下表：

ID、开始、结束
123, 1, N

其中N为整数，编写查询返回如下结果集：

ID、开始、结束
123, 1, 1
123, 1, 2
123, 1, 3
.
.
.
123、1、N

我们使用的平台是 SQL Server 2005，但如果你能用另一种风格的 SQL 做到这一点，我仍然会对解决方案感兴趣。

Answer 1

试试这个：

create table #smalltable (id int, [begin] int, [end] int)
insert into #smalltable values (123,1,4)
insert into #smalltable values (124,1,12)
insert into #smalltable values (125,1,7)

;WITH digits (d) AS (
    SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION
    SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION
    SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION
    SELECT 0)
SELECT
    s.id, s.[begin], n.Number AS [End]
    FROM (SELECT i.d + ii.d * 10 + iii.d * 100 + iv.d * 1000 +
              v.d * 10000 + vi.d * 100000 AS Number
              FROM digits            i
                  CROSS JOIN digits  ii
                  CROSS JOIN digits  iii
                  CROSS JOIN digits  iv
                  CROSS JOIN digits  v
                  CROSS JOIN digits  vi
         ) AS N
        INNER JOIN #smalltable                                    s  ON 1=1
        INNER JOIN (SELECT MAX([end]) AS MaxEnd FROM #smalltable) dt ON 1=1
   WHERE n.Number > 0 AND n.Number<=dt.MaxEnd
    AND n.Number<=s.[end]
   ORDER BY s.id,n.Number

cmets

• 不要将您的列命名为保留字：“开始”和“结束”，总有一天你会感谢我的。
• 如果您计划在生产环境中多次运行，create a Numbers table
  并改用此查询：

必须有一个表格 Numbers 才能工作（见上面的链接）

SELECT
    s.id,s.[begin],n.Number AS [End]
    FROM Numbers                n
        INNER JOIN #smalltable  s ON 1=1
   WHERE  n.Number > 0 AND n.Number<=s.[end]
   ORDER BY s.id,number

它会运行得更好。

Answer 2

给定一些（理论上是无限的，但您可以预先填充）包含所有整数的表格整数，答案相当简单：

SELECT ID, Begin, I FROM YourTable, Integers
WHERE I <= Begin AND I >= End

使用 Integers.I 上的聚集索引，这应该非常快。您可以在存储过程中预填充整数（基于SELECT max(End) FROM YourTable 的结果）。

Answer 3

这将达到 99,999，您可以轻松修改它以添加更多数字。它不需要预先存在的数字表和存储过程，而且速度仍然非常快。至少可以在 SQL Server 2000 及更高版本上运行，并且可以轻松移植到其他风格的 SQL：

select MyTable.ID, MyTable.[Begin], n.N
from (
    select 123 as ID, 1 as [Begin], 9 as [End]
) MyTable
cross join (
    select a.a + (10 * b.a) + (100 * c.a) + (1000 * d.a) + (10000 * e.a) as N
    from (select 0 as a union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) as a
    cross join (select 0 as a union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) as b
    cross join (select 0 as a union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) as c
    cross join (select 0 as a union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) as d
    cross join (select 0 as a union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) as e
) n
where n.N > 0
    and n.N <= MyTable.[End]
order by n.N