Question

以下是表中的示例数据集：

|  callid    |   called     |   calling   |        end          | 
|------------|--------------|-------------|---------------------|
| 1411482360 | 001143792042 | 08444599175 | 2014-07-31 13:55:03 |
| 1476992122 | 001143792042 | 08441713191 | 2014-07-31 14:05:10 |

到目前为止，我已设法获得前一行值，我还需要下一行值。这是我的疑问：

SELECT c.called as customer, c.calling as company, DATE_FORMAT(c.`end`,'%Y-%m-%d') as _date,
        @G := if(@prevComp <> c.calling AND @prevCust = c.called AND @prevDate = DATE_FORMAT(c.`end`,'%Y-%m-%d'), 1, 0) as Gain,
        @prevCust := c.called as prevCust,
        @prevComp := c.calling as prevComp,
        @prevDate := DATE_FORMAT(c.`end`,'%Y-%m-%d') as prevDate
FROM cdrdata_archive c CROSS JOIN
     (SELECT @prevComp := NULL, @prevCust := NULL, @prevDate := NULL) prevVals
ORDER BY c.called, c.`end`

以上查询返回以下结果集：

Customer     Company      Date        prevCust     prevComp     prevDate     Gain

00140443360  08434599117  2014-01-28  00140443360  08434599117  2014-01-28   0
00475172558  08434599218  2014-01-27  00475172558  08434599218  2014-01-27   0
00475172558  08434593455  2014-01-27  00475172558  08434599118  2014-01-27   1

我需要上一行和下一行值来计算每个公司的丢失和获得的呼叫。我设法获得了正确的增值，但计算Lost值（类似于Gain但在新列中），我需要下一个客户，公司和日期。

这可以在没有太大成本的情况下适用于此查询，还是需要重写它？

Answer 1

使用MySQL LIMIT子句进行研究。您的行将返回ORDER BY，因此您确实有订单，但您没有“列表中的数字”，LIMIT是

所以你有了你的查询 - 并且在你追加的SQL末尾

LIMIT $x, 1你有LIMIT <offset>, <count>所以你的计数就是你的行（1），每当你转到'下一行'时你都会改变

$x = $x + 1

希望这会有所帮助。 http://www.mysqltutorial.org/mysql-limit.aspx

因此，您所显示类型的第三次查询将是：

SELECT c.called as customer, c.calling as company, DATE_FORMAT(c.`end`,'%Y-%m-%d') as _date,
        @G := if(@prevComp <> c.calling AND @prevCust = c.called AND @prevDate = DATE_FORMAT(c.`end`,'%Y-%m-%d'), 1, 0) as Gain,
        @prevCust := c.called as prevCust,
        @prevComp := c.calling as prevComp,
        @prevDate := DATE_FORMAT(c.`end`,'%Y-%m-%d') as prevDate
FROM cdrdata_archive c CROSS JOIN
     (SELECT @prevComp := NULL, @prevCust := NULL, @prevDate := NULL) prevVals
ORDER BY c.called, c.`end` LIMIT 2,1

MySql：获取下一行值

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