如何執行查詢以獲取最新數據？

Question

mytable的：

DATE  NAME POCKET1 POCKET2 LOCATION 
1/1/2010 john 5   30  home 
2/1/2010 John 4   10  school 
3/1/2010 john 2   20  mall 

我需要幫助查詢myTable，得到如預期的結果。 我知道如何獲得平均值，但不知道如何獲得最新的LOCATION。

select NAME,max(POCKET1),avg(POCKET2) from myTable 
where NAME = 'john' group by NAME; 

預期結果：

NAME max(POCKET1) avg(POCKET2) LatestLOCATION 
john 5    20    mall 

Answer 1

按日期倒序

select 
    NAME 
    ,max(POCKET1) 
    ,avg(POCKET2) 
    , (select location from mytable order by date desc limit 1) as Location 
from myTable 
where NAME = 'john' group by NAME; 

獲得最佳1級，如果你想獲得約翰

select 
     NAME 
     ,max(POCKET1) 
     ,avg(POCKET2) 
     , (select location from mytable y where y.name = x.name order by date desc limit 1) as Location 
    from myTable x 
    where NAME = 'john' group by NAME;