Question

这是我的表名tblPE

PEID |idnum  | PE_DATE_EXAM   | ATTENDANCE       
1    | 39    | 2014-08-01     | PRESENT       
2    | 42    | 2014-08-10     | ABSENT            
3    | 39    | 2014-08-12     | PRESENT           
4    | 43    | 2014-08-05     | PRESENT        
5    | 42    | 2014-07-15     | NULL           
6    | 39    | 2014-07-03     | ABSENT       
7    | 41    | 2014-08-01     | PRESENT

我想选择最大的PE_DATE_EXAM值，其中idnum = 39且ATTENDANCE = PReSENT

结果应该是：

PEID |idnum  | PE_DATE_EXAM   | ATTENDANCE
-------------------------------------------
3    | 39    | 2014-08-12     | PRESENT

Answer 1

对于单个记录返回，您可以使用LIMIT：

SELECT * FROM tblPE t
WHERE t.idnum = 39 AND t.ATTENDANCE = 'PRESENT'
ORDER BY t.PE_DATE_EXAM DESC
LIMIT 1;

如果您希望所有idnum动态，则可以使用NOT EXISTS()：

SELECT * FROM tblPE t
WHERE NOT EXISTS(SELECT 1 FROM tblPE s
                 WHERE t.idnum = s.idnum AND s.ATTENDANCE = 'PRESENT')
  AND t.attendance = 'PRESENT'

Answer 2

select PEID,IDNUM,PE_DATE_EXAM,ATTENDANCE
from
(select PEID,IDNUM,PE_DATE_EXAM,ATTENDANCE,dense_rank() over(order by PE_DATE_EXAM desc) rnum
from TBLPE
order by PE_DATE_EXAM desc)
where rnum = '1';

此查询是根据您的查询结果编写的。如果您需要任何澄清，请告诉我。

如何选择具有最大日期的行

2 个答案: