Question

我有下表

GroupID Sequence    Name
1             10        Mary
1             25        Jack
1             17        Jill
2              3        Peter
2             42        Henry
2             50        Paul

以下查询返回给定组（1）和给定序列17的下一个最低序列（10）的行

SELECT TOP 1 *
FROM   dbo.customerassignmentgroup
WHERE  groupid = 1
       AND SEQUENCE < (SELECT MAX(SEQUENCE)
                       FROM   dbo.customerassignmentgroup i
                       WHERE  i.groupid = customerassignmentgroup .groupid)
       AND manualsequence < 17
ORDER  BY SEQUENCE DESC

还有另一种方法吗？我想避免

在哪里i.groupid = customerassignmentgroup .groupid

内部查询中的

因为我需要将其转换为SubSonic中的查询

注意：我的数据库是SQL Server 2000

Answer 1

如果你像使用ORDER BY一样，你可以这样做：

SELECT TOP 1 *
FROM   dbo.customerassignmentgroup
WHERE  groupid = 1 AND SEQUENCE < 17
ORDER  BY SEQUENCE DESC

您可以通过执行以下操作来避免使用排序：

SELECT *
FROM   dbo.customerassignmentgroup t1
WHERE  t1.groupid = 1
   AND t1.SEQUENCE = (SELECT MAX(t2.SEQUENCE)
                   FROM   dbo.customerassignmentgroup t2
                   WHERE  t2.groupid = 1 AND t2.SEQUENCE < 17)

Answer 2

还有另一种方法可以做到这一点，但我不知道这是否有助于SubSonic。基本上将子查询移动到FROM。

SELECT TOP 1 *
FROM   dbo.customerassignmentgroup i
       INNER JOIN (SELECT MAX(SEQUENCE) SEQUENCE, groupid
                       FROM   dbo.customerassignmentgroup
                       GROUP BY groupid) maxSeq
       ON  i.groupid = maxSeq.groupid
          and i.SEQUENCE < maxSeq.SEQUENCE 
          and i.groupid = maxSeq.groupid

WHERE  groupid = 1

       AND manualsequence < 17
ORDER  BY SEQUENCE DESC

SQL Server：查询给定参数的下一个最低值

2 个答案: