从同一sql表中获取不同列的最新值和最早值

我有一张可以选择日期的桌子。我希望能够应用WHERE语句返回一组数据，然后从一列返回最早的日期，从另一列返回最晚的日期。下面是一个示例表：

ID  StartDate   EndDate     Person   Subject
1   01/03/2010  03/03/2010   Paul    Math
2   12/05/2010  22/05/2010   Steve   Science
3   04/03/2010  08/03/2010   Paul    English

---

所以我想返回Person='Paul'的所有记录。但是返回类似于（最早的）StartDate=01/03/2010（来自记录ID 1）和（最晚的）EndDate=08/03/2010（来自记录ID 3）和Subject=English（来自记录3）。我需要两行Paul和上面的数据和Id。需要person='Paul'的所有行

预期结果：

ID  StartDate   EndDate Person  Subject
1   2010-03-01  2010-03-08  Paul    English
3   2010-03-01  2010-03-08  Paul    English

在下面的sql查询中，您是否发现与性能（数百万条记录）有关的任何问题：

 Select PT3.ID,PT4.EarliestStartDate AS StartDate,PT4.EndDate,PT4.Person,PT4.Subject from Data AS PT3 
Join( SELECT Top 1 with ties * FROM Data AS PT  
Join( SELECT PT1.Person as Person1, MIN(PT1.StartDate ) as EarliestStartDate FROM Data AS PT1 where Person ='Paul' group by PT1.Person)  AS PT2 ON  PT.Person =PT2.Person1WHERE Person  ='Paul'
  Order By Row_Number() over (Partition By PT.Person Order By PT.EndDate desc)) AS PT4 ON PT3.Person = PT4.Person 

这可能会起作用：

首先执行

分组

，以获取每个人所需的日期

将分组移动到公共表表达式（

cte

）

使用完整数据集连接回以获取所有行

对于每个结果记录，使用交叉应用选择相应的主题

可选：筛选所需人员（

where

子句）

样本数据

create table Data
(
  ID int,
  StartDate date,
  EndDate date,
  Person nvarchar(10),
  Subject nvarchar(10)
);

insert into Data (ID, StartDate, EndDate, Person, Subject) values
(1, '2010-03-01', '2010-03-03', 'Paul',  'Math'),
(2, '2010-05-12', '2010-05-22', 'Steve', 'Science'),
(3, '2010-03-04', '2010-03-08', 'Paul',  'English');

解决方案

with cte as
(
  select min(d.StartDate) as StartDate,
         max(d.EndDate) as EndDate,
         d.Person
  from Data d
  group by d.Person
)
select d.Id,
       c.StartDate,
       c.EndDate,
       c.Person,
       x.Subject
from cte c
join data d
  on d.Person = c.Person
cross apply ( select top 1 d2.Subject
              from Data d2
              where d2.Person = c.Person
                and d2.EndDate = c.EndDate ) x
where d.Person = 'Paul'
order by d.Person;

---

查看它的运行情况。

这将为您提供正确的值

DECLARE @values TABLE (
    Id INT,
    StartDate DATETIME2,
    EndDate DATETIME2,
    Person NVARCHAR(MAX),
    Subject NVARCHAR(MAX))

INSERT INTO @values VALUES 
(1, '2010-03-01', '2010-03-03', 'Paul', 'Math'),
(2, '2010-05-12', '2010-05-22', 'Steve', 'Science'),
(3, '2101-03-04', '2010-03-08', 'Paul', 'English')

;WITH sort AS (
    SELECT
        Person,
        MIN(StartDate) OVER(PARTITION BY Person) StartDate,
        MAX(EndDate) OVER(PARTITION BY Person) EndDate,
        Subject,
        ROW_NUMBER() OVER(PARTITION BY Person ORDER BY EndDate DESC) rownum
    FROM @values v)

SELECT
    Person,
    StartDate,
    EndDate,
    Subject
FROM sort
WHERE rownum = 1

它将为您提供以下结果：

Person  MinStartDate    MaxEndDate   Subject
Paul    2010-03-01      2010-03-08   English
Steve   2010-05-12      2010-05-22   Science

---

如果您只关心选择Pauls数据，这就足够了：

SELECT 
   Person,
   MIN(startDate) AS Earliest, 
   MAX(EndDate) AS Latest, 
   (
      SELECT TOP 1 Subject 
      FROM Data
      WHERE Person = 'Paul'
      ORDER BY EndDate DESC
   ) AS Subject
FROM Data WHERE Person = 'Paul'

如果要选择所有人员，则此操作应有效：

SELECT 
   d1.Person,
   MIN(d1.startDate) AS Earliest, 
   MAX(d1.EndDate) AS Latest, 
   (
      SELECT TOP 1 d2.Subject 
      FROM Data d2
      WHERE d2.Person = d1.Person
      ORDER BY EndDate DESC
   ) AS Subject
FROM Data d1
GROUP BY d1.Person

编辑：您似乎希望表中的每一行都有结果，而不是每人一行，但始终显示最早和最晚的日期。这就是你想要的吗

SELECT 
   d1.Id,
   d1.Person,
   (
      SELECT MIN(d1.StartDate) AS Earliest
      FROM Data d2
      WHERE d2.Person = d1.Person
   ) AS Earliest,
   (
      SELECT MAX(d1.EndDate) AS Latest
      FROM Data d2
      WHERE d2.Person = d1.Person
   ) AS Latest,
   (
      SELECT TOP 1 d2.Subject 
      FROM Data d2
      WHERE d2.Person = d1.Person
      ORDER BY EndDate DESC
   ) AS Subject
FROM Data d1

---

请显示您的查询声音，如“分组依据”和“最小/最大”。因此，您希望获得最早的开始日期和最新的结束日期，而不考虑主题？然后分别获取最新结束日期的主题？预期结果是什么？需要person='Paul'的所有行您当前的版本无法解决问题的

主题

部分。@Kristofer我如何才能在查询的相同结果集中获得Paul的所有Id（其他列值将相同）？您的答案不包含有效的SQL语法（提示：文本字符串

Paul

需要引号）。@Sander我修复了它，并将Person列添加到result@Fuzzy我已经用预期结果更新了问题我已经添加了预期结果和我的查询