SQL Server根据日期时间和用户类型选择记录

Question

 id| type | datetime | 
    ---| ---------|--------------| 
    1 | admin | 2016-01-03 | 
    2 | user  | 2016-01-07 | 
    3 | user  | 2016-01-08 | 
    4 | admin | 2016-01-04 | 
    5 | user  | 2016-01-01 | 
    6 | user  | 2016-01-03 | 
    7 | user  | 2016-01-05 | 
    8 | user  | 2016-01-09 | 

可以说我有一个表，我需要根据日期时间重新排列它。第一条记录必须来自管理员，其中最新的日期时间仅限于管理员类型。然后第二个到第五个记录必须从用户排序的类型中按照它们的日期时间降序排列。然后再次，第六条记录必须从第二个最新的日期时间的管理类型。查询的预期结果显示在下表中。

预期结果：

 id| type | datetime | 
    ---| ---------|--------------| 
    4 | admin | 2016-01-04 | 
    8 | user  | 2016-01-09 | 
    3 | user  | 2016-01-08 |   
    2 | user  | 2016-01-07 | 
    1 | admin | 2016-01-03 | 
    7 | user  | 2016-01-05 | 
    6 | user  | 2016-01-03 | 
    5 | user  | 2016-01-01 | 

你们可以给我如何编写查询来获得期望的结果一些想法？

Answer 1

我发现了一个办法做到这一点而不NTILE的问题时，你的计数不是你想组的用户的数量整除。基于gofr1的脚本，这是我建议你使用的：

SELECT id, 
     [type], 
     [datetime] 
FROM (
    SELECT id, 
      [type], 
      [datetime], 
      ROW_NUMBER() OVER (ORDER BY [datetime]) - 1 Idx 
    FROM YourTable 
    WHERE [type] = 'admin' 
    UNION ALL 
    SELECT id, 
      [type], 
      [datetime], 
      FLOOR((ROW_NUMBER() OVER (ORDER BY [datetime]) - 1)/3) Idx 
    FROM YourTable 
    WHERE [type] = 'user' 
    ) as p 
ORDER BY Idx, [type] 

Answer 2

你可以在样使用NTILE在它下面2组分配行，然后你只需要通过组号和日期时间订购吧：

SELECT id, 
     [type], 
     [datetime] 
FROM (
    SELECT id, 
      [type], 
      [datetime], 
      NTILE(2) OVER (ORDER BY [datetime] DESC) as NT 
    FROM YourTable 
    WHERE [type] = 'admin' 
    UNION ALL 
    SELECT id, 
      [type], 
      [datetime], 
      NTILE(2) OVER (ORDER BY [datetime] DESC) as NT 
    FROM YourTable 
    WHERE [type] = 'user' 
    ) as p 
ORDER BY NT, [type] 

输出：

id type datetime 
4 admin 2016-01-04 
8 user 2016-01-09 
3 user 2016-01-08 
2 user 2016-01-07 
1 admin 2016-01-03 
7 user 2016-01-05 
6 user 2016-01-03 
5 user 2016-01-01 

注：如果您需要动态确定组编号（根据行数计算），可以使用以下代码：

DECLARE @i int 

SELECT @i = --some number 

NTILE(@i) OVER (ORDER BY ... 

我建议使用：

SELECT @i = CAST(CASE WHEN COUNT(*)%4.00 = 1 THEN ROUND(COUNT(*)/4.00,0)+1 ELSE ROUND(COUNT(*)/4.00,0) END as int) 
FROM YourTable