Question

我有一个显示一个客户的第二个结果的查询。我现在需要做的是在特定列表中显示每个客户的第二个结果（例如20个不同的客户G / 1931，G / 1932，G / 1933等）。

我该怎么做？ Sql Server 2000通过SSMS 2005

1位客户的当前查询是

SELECT TOP 1 link_to_client, call_ref
FROM
(
    SELECT TOP 2 link_to_client, call_ref
    FROM calls WITH (NOLOCK)
    WHERE link_to_client IN ('G/1931')
        AND call_type = 'PM'
    ORDER BY call_ref DESC
) x
ORDER BY call_ref

Answer 1

我认为最有效的方法是排除每个call_ref的最低link_to_client，然后取最小值：

SELECT  calls.link_to_client, 
        MAX(calls.Call_Ref) call_ref
FROM    calls WITH (NOLOCK)
        LEFT JOIN 
        (   SELECT  link_to_client, MAX(Call_Ref) call_ref
            FROM    calls WITH (NOLOCK)
            WHERE   calls.call_type = 'PM'
            GROUP BY link_to_client
        ) MaxCalls
            ON MaxCalls.link_to_client = calls.link_to_client
            AND MaxCalls.Call_ref = calls.call_ref
WHERE   calls.call_type = 'PM'
AND     MaxCalls.link_to_Client IS NULL
GROUP BY calls.link_to_Client;

但是如果你想扩展这个以获得，例如每个客户的第5个，那么它将开始变得混乱。在这种情况下，我会使用：

SELECT  calls.link_to_client, calls.call_ref
FROM    calls
WHERE   5 = (   SELECT  COUNT(*)
                FROM    calls c2
                WHERE   c2.link_to_Client = calls.link_to_Client
                AND     c2.call_ref <= calls.call_ref
            );

我的最后建议是升级到更新版本的SQL-Server，您可以使用ROW_NUMBER！

Examples on SQL Fiddle

感谢小提琴的Nenad Zivkovic

显示多条记录的第二个结果

1 个答案: