SQL：如何从表中获取最大值

Question

 值来自TABLE contract，tenant，property 那么我想根据每个idproperty得到max（expiry_date） 输出如：

idproperty| property_unit | tenant| expiry_date | idcontract   
 426      |  Car Park     | NGUY  | 2016-05-27  |   1578    
 432      | 13TH FLoor    | wong  | 2015-09-21  |   1455    
 433      | 14TH floor    | HA    | 2016-07-01  |   1629

感谢您的帮助!!

Answer 1

试试这个。使用OVER PARTITION BY查找每个property_unit的max expire_date

SELECT idproperty,
       property_unit,
       tenant,
       expiry_date,
       idcontract
FROM  (SELECT Row_number() OVER (partition BY idproperty, property_unit
                  ORDER BY expiry_date DESC) Rn,
              *
       FROM   tablename) a
WHERE  a.rn = 1