Question

在SQL Server中，我有两个表。一个“主”表，包含所有数据和每个条目唯一id。另一个表是审计日志，其中来自main的id将多次存储在审计表中。

我的查询如下：

SELECT 
    a.title, a.id, a.name, t.user, t.time  
FROM 
    MainTable a      
INNER JOIN 
    AuditLog AS t ON a.id = t.id    
WHERE 
    a.NAME LIKE 'Something%'  
    AND a.ACTIVE = 'Y'

结果如下：

TITLE           ID          NAME         USER          TIME
----------------------------------------------------------------
Something1      someth1     Some 1       User5         468534771
Something1      someth1     Some 1       User7         468574887
Something2      someth2     Some 2       User6         468584792

返回ID的多个结果。我只想要最早的（来自AuditLog）条目而不是每个条目。所以我想要的结果如下：

TITLE           ID          NAME         USER          TIME
----------------------------------------------------------------
Something1      someth1     Some 1       User5         468534771
Something2      someth2     Some 2       User6         468584792

如何做到这一点？我正在尝试连接中的一些子查询。

Answer 1

在sql server 2005+中，您可以使用row_number()

select title, id, name, user, time
from
(
  SELECT a.title, a.id, a.name, t.user, t.time,
    row_number() over(partition by a.id order by t.time) rn
  FROM MainTable a
  INNER JOIN AuditLog AS t
    ON a.id = t.id
  WHERE a.NAME LIKE 'Something%'
    AND a.ACTIVE='Y'
) src
where rn = 1

请参阅SQL Fiddle with Demo

或者您可以使用子查询来获取最短时间：

SELECT a.title, a.id, a.name, l.user, l.time
FROM MainTable a 
INNER JOIN AuditLog l
  ON a.id = l.id
INNER JOIN
(
  select min(time) Mintime, id
  from AuditLog
  group by id
) AS t 
  ON l.id = t.id
  AND l.time = t.mintime
WHERE a.NAME LIKE 'Something%' 
  AND a.ACTIVE='Y';

Answer 2

SELECT TOP 1 a.title, a.id, a.name, t.user, t.time
FROM MainTable a
INNER JOIN AuditLog AS t
ON a.id = t.id
WHERE a.NAME LIKE 'Something%'
AND a.ACTIVE='Y'
ORDER BY T.DATE DESC

Answer 3

您可以使用outer apply，例如：

select  *
from    MainTable a
outer apply
        (
        select  top 1 *
        from    AuditLog t
        where   a.id = t.id
        order by
                t.time
        ) t
where   a.name like 'Something%'
        and a.active = 'y'

Answer 4

试一试

SELECT a.title, a.id, a.name, t.user, t.time  
FROM MainTable a      
    JOIN AuditLog AS t ON a.id = t.id
        JOIN (SELECT ID, MAX(TIME) AS LASTTIME FROM AUDITLOG) AS c 
        ON c.ID =  t.id AND c.LASTTIME = t.time    
WHERE a.NAME LIKE 'Something%'  
    AND a.ACTIVE = 'Y'

表连接;从加入中选择1个条目

4 个答案: