sql

Question

有如下表记录: 
ID Name EmailAddress LastLogon 
100 test4 [email protected] 2007-11-25 16:31:26 
13 test1 [email protected] 2007-3-22 16:27:07 
19 test1 [email protected] 2007-10-25 14:13:46 
42 test1 [email protected] 2007-11-20 14:20:10 
45 test2 [email protected] 2007-4-25 14:17:39 
49 test2 [email protected] 2007-5-25 14:22:36 用一句sql查询出每个用户最近一次登录的记录(每个用户只显示一条最近登录的记录) 

Answer 1

select * from Table where time=(select max(time) from Table) 

Answer 2

所谓授人以渔不如授人以渔，这个问题简单。你用分组就行了 groug by ，不会的话我再把答案公布吧。

Answer 3

-- Create table
create table THINK_TEST
(
  ID           VARCHAR2(50),
  NAME         VARCHAR2(20),
  EMAILADDRESS VARCHAR2(50),
  LASTLOGON    VARCHAR2(50)
)
-- insert data
insert into think_test values('100','test4','[email protected]','2007-11-25 16:31:26 ');
insert into think_test values('13','test1','[email protected]','2007-3-22 16:27:07');
insert into think_test values('19','test1','[email protected]','2007-10-25 14:13:46');
insert into think_test values('42','test1','[email protected]','2007-11-20 14:20:10');
insert into think_test values('45','test2','[email protected]','2007-4-25 14:17:39');
insert into think_test values('49','test2','[email protected]','2007-5-25 14:22:36 ');
--preview date
select * from think_test;ID                                                 NAME                 EMAILADDRESS                                       LASTLOGON
-------------------------------------------------- -------------------- -------------------------------------------------- --------------------------------------------------
100                                                test4                [email protected]                                     2007-11-25 16:31:26
13                                                 test1                [email protected]                                     2007-3-22 16:27:07
19                                                 test1                [email protected]                                     2007-10-25 14:13:46
42                                                 test1                [email protected]                                     2007-11-20 14:20:10
45                                                 test2                [email protected]                                     2007-4-25 14:17:39
49                                                 test2                [email protected]                                     2007-5-25 14:22:36
--execute sql
select *
from(
 select t.*,RANK() OVER (PARTITION BY t.name order by rownum desc) Rnk        
 from think_test t
) tt
where tt.rnk<2;ID                                                 NAME                 EMAILADDRESS                                       LASTLOGON                                                 RNK
-------------------------------------------------- -------------------- -------------------------------------------------- -------------------------------------------------- ----------
42                                                 test1                [email protected]                                     2007-11-20 14:20:10                                         1
49                                                 test2                [email protected]                                     2007-5-25 14:22:36                                          1
100                                                test4                [email protected]                                     2007-11-25 16:31:26                                         1

Answer 4

select ID,Name,EmailAddress,max(LastLogon) from table  group by Name;亲测，可以。前提是你的Name是独立的，如果有两人名字相同那就是特例。给分吧