Question

表定义

ColumnName  Comments
CustomerID  INT
SequenceNo  INT
Comments    VARCHAR(MAX)

CUSTOMER TABLE

CustomerID  SequenceNo  Comments
1   1   ABC D
1   2   CDE
1   3   ABC
1   4   ABC D
1   5   CDE
1   6   abc
2   7   ABC DEF
2   8   
2   9   ABC DEF
2   10  DEF
2   11  XYZ 123
2   12  ABC
3   13  PQ RST

输出

CustomerID  SequenceNo  Comments
1   3   ABC
1   4   ABC D
1   5   CDE
1   6   abc
2   8   
2   9   ABC DEF
2   10  DEF
2   11  XYZ 123
2   12  ABC
3   13  PQ RST

应过滤记录 1.仅显示所有客户的客户表中的唯一注释， 2.如果注释相同，则显示具有最大SequenceNo

的行

Answer 1

这假设您使用区分大小写的排序规则

SELECT CustomerID,
       MAX(SequenceNo) AS SequenceNo,
       Comments
FROM yourTable
GROUP BY CustomerID,Comments
ORDER BY CustomerID,MAX(SequenceNo)

如果您没有使用区分大小写的排序规则，请尝试以下操作：

SELECT CustomerID,
       MAX(SequenceNo) AS SequenceNo,
       Comments COLLATE SQL_Latin1_General_CP1_CS_AS
FROM yourTable
GROUP BY CustomerID,Comments COLLATE SQL_Latin1_General_CP1_CS_AS
ORDER BY CustomerID,MAX(SequenceNo)

Answer 2

您可以使用窗口函数：

select c.*
from (select c.*,
             row_number() over (partition by CustomerId, Comments
                                order by SequenceNo desc) as seqnum
      from comments c
     ) c
where seqnum = 1;

查询以根据特定条件显示唯一注释

2 个答案: