如何获取最后一次相关更新和倒数第二次相关更新答案

【问题标题】：How to get last related update and second last related update如何获取最后一次相关更新和倒数第二次相关更新
【发布时间】：2014-03-20 13:21:37
【问题描述】：

我有 3 张桌子：opportunities、tr_opportunity_updates 和
opportunities_tr_opportunity_updates_1_c。后者将opportunities 与opportunity_updates 关联起来。

我想获得 3 列，第一列是机会名称，第二列是对机会进行的最后更新，第三列是对机会进行的最后更新。

我正在尝试获得以下输出：

  -----------------------------------------------
  Opportunity | Last_Update | Second_Last update 
  -----------------------------------------------
  Opp1        | update      | second bla bla     
  -----------------------------------------------
  Opp2        | Lastest up. | second bla bla

我有一个查询，它获取机会名称和最后一次更新，但我不知道如何获取第二个最后更新并将其添加为另一列。这会是一个子查询吗？如果是的话如何：

  SELECT opportunities.name AS Opportunity, tr_opportunity_updates.description AS Last_Update
  FROM opportunities
  LEFT JOIN opportunities_tr_opportunity_updates_1_c ON opportunities_tr_opportunity_updates_1_c.opportunities_tr_opportunity_updates_1opportunities_ida = opportunities.id
  LEFT JOIN tr_opportunity_updates ON opportunities_tr_opportunity_updates_1_c.opportunities_tr_opportunity_updates_1tr_opportunity_updates_idb = tr_opportunity_updates.id
  WHERE opportunities.deleted = 0
  GROUP BY opportunities.name
  LIMIT 0 , 30

我试图为此实现一个 sql fiddle，但我的表和数据太大了，有许多不敬的字段，但是除了 date_created 之外，与上述查询相关的所有信息都在所有表中，可能需要获取最后第二次更新？

【问题讨论】：

标签： mysql sql sugarcrm

【解决方案1】：

由于没有人试图提供帮助，我将发布我自己的答案：

 SELECT oppa.name AS Opportunity, tr_opportunity_updates.description AS Last_Update,
 (SELECT tou.description FROM opportunities oppb
 LEFT JOIN opportunities_tr_opportunity_updates_1_c ON opportunities_tr_opportunity_updates_1_c.opportunities_tr_opportunity_updates_1opportunities_ida = oppb.id LEFT JOIN tr_opportunity_updates tou ON opportunities_tr_opportunity_updates_1_c.opportunities_tr_opportunity_updates_1tr_opportunity_updates_idb = tou.id
 WHERE oppb.deleted =0 AND tou.deleted =0 AND oppb.id = oppa.id
 ORDER BY tou.date_modified Desc LIMIT 1,1) AS Second_Last_Update
 FROM opportunities oppa
 LEFT JOIN opportunities_tr_opportunity_updates_1_c ON opportunities_tr_opportunity_updates_1_c.opportunities_tr_opportunity_updates_1opportunities_ida = oppa.id
 LEFT JOIN tr_opportunity_updates ON opportunities_tr_opportunity_updates_1_c.opportunities_tr_opportunity_updates_1tr_opportunity_updates_idb = tr_opportunity_updates.id
 WHERE oppa.deleted =0 AND tr_opportunity_updates.deleted =0
  GROUP BY oppa.name

【讨论】：