Sql 使用“选择顶部”生成一个参数列表，其中

我有一张这样的桌子：

|    date   | example_variable |
| 2013-2-22 |       cat        |
| 2013-3-22 |       dog        |
| 2013-1-22 |       ewe        |
| 2013-8-22 |       pig        |

|    date   |      rank        | example_variable  |
| 2013-2-22 |      1           |       cat1        |
| 2013-2-22 |      2           |       cat2        |
| 2013-3-22 |      1           |       dog1        |
| 2013-3-22 |      2           |       dog2        |
| 2013-1-22 |      1           |       ewe1        |
| 2013-1-22 |      2           |       ewe2        |
| 2013-8-22 |      1           |       pig1        |
| 2013-8-22 |      2           |       pig2        |

SELECT
a.rank, b.rank, c.rank,
a.example_variable as V1,
b.example_variable as V2,
c.example_variable as V3, 
a.AsOfDate as 1stDate,     
b.AsOfDate as 2ndDate,
c.AsOfDate as 3rdDate
FROM <table> a, <table> b, <table> c
WHERE a.rank = b.rank,
And b.rank = c.rank,
AND a.AsOfDate = '2013-1-22'
AND b.AsOfDate = '2013-2-22'
AND c.AsOfDate = '2013-3-22'

我已经知道怎么做了：

SELECT
a.example_variable as V1,
b.example_variable as V2,
c.example_variable as V3, 
a.AsOfDate as 1stDate,     
b.AsOfDate as 2ndDate,
c.AsOfDate as 3rdDate
FROM <table> a, <table> b, <table> c
WHERE a.AsOfDate = '2013-1-22'
AND b.AsOfDate = '2013-2-22'
AND c.AsOfDate = '2013-3-22'

在上面的查询中，我手动输入了最近的三个日期。我想自动找到那些。看起来我可以用陀螺，但我不知道怎么用

更复杂的版本：

我简化了上面的例子。在我的现实世界中，有多行具有相同的日期，其组织方式如下：

|    date   | example_variable |
| 2013-2-22 |       cat        |
| 2013-3-22 |       dog        |
| 2013-1-22 |       ewe        |
| 2013-8-22 |       pig        |

|    date   |      rank        | example_variable  |
| 2013-2-22 |      1           |       cat1        |
| 2013-2-22 |      2           |       cat2        |
| 2013-3-22 |      1           |       dog1        |
| 2013-3-22 |      2           |       dog2        |
| 2013-1-22 |      1           |       ewe1        |
| 2013-1-22 |      2           |       ewe2        |
| 2013-8-22 |      1           |       pig1        |
| 2013-8-22 |      2           |       pig2        |

SELECT
a.rank, b.rank, c.rank,
a.example_variable as V1,
b.example_variable as V2,
c.example_variable as V3, 
a.AsOfDate as 1stDate,     
b.AsOfDate as 2ndDate,
c.AsOfDate as 3rdDate
FROM <table> a, <table> b, <table> c
WHERE a.rank = b.rank,
And b.rank = c.rank,
AND a.AsOfDate = '2013-1-22'
AND b.AsOfDate = '2013-2-22'
AND c.AsOfDate = '2013-3-22'

查询如下：

|    date   | example_variable |
| 2013-2-22 |       cat        |
| 2013-3-22 |       dog        |
| 2013-1-22 |       ewe        |
| 2013-8-22 |       pig        |

|    date   |      rank        | example_variable  |
| 2013-2-22 |      1           |       cat1        |
| 2013-2-22 |      2           |       cat2        |
| 2013-3-22 |      1           |       dog1        |
| 2013-3-22 |      2           |       dog2        |
| 2013-1-22 |      1           |       ewe1        |
| 2013-1-22 |      2           |       ewe2        |
| 2013-8-22 |      1           |       pig1        |
| 2013-8-22 |      2           |       pig2        |

SELECT
a.rank, b.rank, c.rank,
a.example_variable as V1,
b.example_variable as V2,
c.example_variable as V3, 
a.AsOfDate as 1stDate,     
b.AsOfDate as 2ndDate,
c.AsOfDate as 3rdDate
FROM <table> a, <table> b, <table> c
WHERE a.rank = b.rank,
And b.rank = c.rank,
AND a.AsOfDate = '2013-1-22'
AND b.AsOfDate = '2013-2-22'
AND c.AsOfDate = '2013-3-22'

---

编辑1：即使使用更复杂的数据版本，您仍应能够使用行编号：

看

如果您没有row_编号，可以使用以下选项：

;with d1 as
(
  select t.date, t.[rank], t.example_variable
  from yt t
  inner join
  (
    select min(date) date, [rank]
    from yt
    group by [rank]
  ) d
    on t.date = d.date
    and t.[rank] = d.[rank]
)
select d1.rank,
  d1.example_variable v1,
  d2.example_variable v2,
  d3.example_variable v3,
  d1.date [1stDate],
  d2.date [2ndDate],
  d3.date [3rdDate]
from d1
cross apply
(
  select top 1 date, [rank], example_variable
  from yt t
  where d1.date < t.date
    and d1.[rank] = t.[rank]
) d2
cross apply
(
  select top 1 date, [rank], example_variable
  from yt t
  where d2.date < t.date
    and d2.[rank] = t.[rank]
) d3;

select d1.example_variable v1,
  d2.example_variable v2,
  d3.example_variable v3,
  d1.date [1stdate],
  d2.date [2nddate],
  d3.date [3rddate]
from
(
  select top 1 date, example_variable
  from yt
  order by date
) d1
cross apply
(
  select top 1 d2.date, d2.example_variable
  from yt d2
  where d1.date < d2.date
  order by d2.date
) d2
cross apply
(
  select top 1 d3.date, d3.example_variable
  from yt d3
  where d2.date < d3.date
  order by d3.date
) d3;

看

如果您没有行\号，则可以使用以下选项：

;with d1 as
(
  select t.date, t.[rank], t.example_variable
  from yt t
  inner join
  (
    select min(date) date, [rank]
    from yt
    group by [rank]
  ) d
    on t.date = d.date
    and t.[rank] = d.[rank]
)
select d1.rank,
  d1.example_variable v1,
  d2.example_variable v2,
  d3.example_variable v3,
  d1.date [1stDate],
  d2.date [2ndDate],
  d3.date [3rdDate]
from d1
cross apply
(
  select top 1 date, [rank], example_variable
  from yt t
  where d1.date < t.date
    and d1.[rank] = t.[rank]
) d2
cross apply
(
  select top 1 date, [rank], example_variable
  from yt t
  where d2.date < t.date
    and d2.[rank] = t.[rank]
) d3;

select d1.example_variable v1,
  d2.example_variable v2,
  d3.example_variable v3,
  d1.date [1stdate],
  d2.date [2nddate],
  d3.date [3rddate]
from
(
  select top 1 date, example_variable
  from yt
  order by date
) d1
cross apply
(
  select top 1 d2.date, d2.example_variable
  from yt d2
  where d1.date < d2.date
  order by d2.date
) d2
cross apply
(
  select top 1 d3.date, d3.example_variable
  from yt d3
  where d2.date < d3.date
  order by d3.date
) d3;

---

请参见

我正在使用Azure SQL。然而，与性能相比，我更喜欢清晰和简单。在我看来，SQL Azure不支持窗口功能。@user1744318此链接显示它受支持-@user1744318查看我的编辑，我添加了一个没有行号的版本。您介意在自己的答案中添加第二个吗？就我的情况而言，第二个是非常可取的。第一个例子为我创造了更多的工作，因为我的真实世界的例子有我的例子中没有的复杂性。提前谢谢，如果我有点奇怪，请原谅。@user1744318实际上我更喜欢将它们保留在同一个答案中，因为它们都是您问题的解决方案。即使一个比另一个更受欢迎，您仍然可以接受：