通過在mysql中的順序選擇大小寫

Question

我正在運行以下查詢以查找用戶的最佳連勝記錄。

$sql="select sub.user_id as user_id,max(sub.streak) as streak,max(sub.units) as units 
       from 
        (
       select 
       case when @x is null then @x:=user_id end, 
       case 
       when awarded_unit>0 and @x=user_id then @y:=@y+1 
       when awarded_unit<0 and @x=user_id then @y:=0 
       when awarded_unit>0 and @x<>user_id then @y:=1 
       when awarded_unit<0 and @x<>user_id then @y:=0 
       end as streak, 
       case 
       when awarded_unit>0 and @x=user_id then @z:=@z+awarded_unit 
       when awarded_unit<0 and @x=user_id then @z:=0 
       when awarded_unit>0 and @x<>user_id then @z:=awarded_unit 
       when awarded_unit<0 and @x<>user_id then @z:=0 
       end as units, 
       @x:=user_id as user_id, 
       awarded_unit 
       from $select_user_events_fights as u,$events as e,$event_fight_table as ef,$post_meta as pm where e.ID=ef.event_id 
       and ef.event_fight_id=u.event_fight_id and e.post_type='bt_events' and pm.post_id = e.ID and e.post_status ='publish' and pm.meta_key='_event_dt_time' and u.`awarded_unit`!=0 and u.season_id=$season_id and u.user_id=".$user->ID." 

       order by pm.meta_value desc,ef.fight_order desc 
       ) as sub 
       group by sub.user_id"; 


      mysql_query("set @y=0;"); 
      mysql_query("set @x=null;"); 
      mysql_query("set @z=0;"); 

如果我把訂單通過u.primary_key它工作正常。但是我希望事件按日期排列並按照順序排序。它在這種情況下會給出錯誤的結果。

我已經檢查了內部查詢語句順序。

通過語句排序（"order by pm.meta_value desc,ef.fight_order desc"），排序結果 經過計算最好的條紋，因此它給出了錯誤的結果。

請解釋如何得到正確的答案和我所缺少的here.Thanks

Answer 1

你需要做的ORDER BY的子查詢，然後在處理該外部查詢執行的條紋檢測。

試試這個（未經檢驗的 - 如果你要我來測試，在sqlfiddle提供一些數據）：

 $sql="select sub.user_id as user_id,max(sub.streak) as streak,max(sub.units) as units 
      from 
       (
      select 
      case when @x is null then @x:=user_id end, 
      case 
      when awarded_unit>0 and @x=user_id then @y:=@y+1 
      when awarded_unit<0 and @x=user_id then @y:=0 
      when awarded_unit>0 and @x<>user_id then @y:=1 
      when awarded_unit<0 and @x<>user_id then @y:=0 
      end as streak, 
      case 
      when awarded_unit>0 and @x=user_id then @z:=@z+awarded_unit 
      when awarded_unit<0 and @x=user_id then @z:=0 
      when awarded_unit>0 and @x<>user_id then @z:=awarded_unit 
      when awarded_unit<0 and @x<>user_id then @z:=0 
      end as units, 
      @x:=user_id as user_id, 
      awarded_unit 
      from (select user_id, awarded_unit 
        from $select_user_events_fights as u,$events as e,$event_fight_table as ef,$post_meta as pm where e.ID=ef.event_id 
      and ef.event_fight_id=u.event_fight_id and e.post_type='bt_events' and pm.post_id = e.ID and e.post_status ='publish' and pm.meta_key='_event_dt_time' and u.`awarded_unit`!=0 and u.season_id=$season_id and u.user_id=".$user->ID." 

        order by pm.meta_value desc,ef.fight_order desc) as subsub 
      ) as sub 
      group by sub.user_id";