Question

我有一个名为License的表，其列为：

    pk_license  
    fk_customer 
    option_1

和值：

    4297    1   0
    30640   1   1
    29990   87  0
    29373   134 0
    2720    144 1
    30579   144 0
    24799   172 0
    30035   183 1
    27855   197 0
    30337   197 1
    30596   198 1
    28083   216 0

我需要获取option_1的值，以获得每个不同fk_customer的最高pk_license。我试过了：

SELECT        *
FROM          License li
INNER JOIN
    (SELECT   opt_2, fk_station, MAX(pk_license) AS MaxLicense
     FROM     License
     GROUP BY opt_2, fk_station) groupedli 
ON li.opt_2 = groupedli.opt_2
AND li.pk_license = groupedli.MaxLicense
ORDER BY li.fk_station

...但我为option_1的每个值获得了两行。我想要做的是确定每个客户的最新option_1值。

Answer 1

试试这个：

SELECT        li.*
FROM          License li
INNER JOIN
    (SELECT   fk_customer,
              max(pk_license) as maxLicense
     FROM  License  
     GROUP BY fk_customer) lm
ON li.fk_customer = lm.fk_customer
AND li.pk_license = lm.MaxLicense
ORDER BY li.fk_customer, li.pk_license

Answer 2

你可以试试这个：

SELECT DISTINCT(`fk_customer`),`pk_license`,`option_1` FROM `License` order by `pk_license` DESC

查询结果：

1   | 30640 | 1
198 | 30596 | 1
144 | 30579 | 0
197 | 30337 | 1
183 | 30035 | 1
87  | 29990 | 0
134 | 29373 | 0
216 | 28083 | 0
197 | 27855 | 0
172 | 24799 | 0
1   | 4297  | 0
144 | 2720  | 1

Answer 3

这是我的解决方案：

Create table tblLicense 
( 
     pk_license  int,
     fk_customer int,
     option_1 int
)
Go 

   Insert into tblLicense values (4297,    1,   0)
   Insert into tblLicense values (30640,  1  ,1)
   Insert into tblLicense values (29990,  87 ,0)
   Insert into tblLicense values (29373,  134,0)
   Insert into tblLicense values (2720 ,  144,1)
   Insert into tblLicense values (30579,  144,0)
   Insert into tblLicense values (24799,  172,0)
   Insert into tblLicense values (30035,  183,1)
   Insert into tblLicense values (27855,  197,0)
   Insert into tblLicense values (30337,  197,1)
   Insert into tblLicense values (30596,  198,1)
   Insert into tblLicense values (28083,  216,0)
    Go


SELECT tblLicense.pk_license,tblLicense.fk_customer,option_1 FROM tblLicense
INNER JOIN 
(
    SELECT fk_customer,MAX(pk_license) as pk_license from tblLicense
    GROUP BY fk_customer
)  groupedTbl
on tblLicense.fk_customer = groupedTbl.fk_customer
AND tblLicense.pk_license = groupedTbl.pk_license
ORDER BY tblLicense.fk_customer

Answer 4

无需执行joins您可以使用相关subquery

select * from table t
where pk_license = 
           (select max(pk_license) from table where fk_customer = t.fk_customer)
order by fk_customer

对于您当前的尝试，您根据可能影响所需结果的两列（group by，opt_2）执行fk_station。

如何从另一列的最高不同值中选择列值

4 个答案: