SQL 查询从同一个表中获取不同的值

Question

Let's say I have this table: employeetable:

empid	joindate	location	HRupdatedate	Changes
1	2002-01-05	Delhi	2021-03-01	New
2	2009-09-09	Mumbai	2021-03-05	New
1	2010-06-27	Hyderabad	2021-03-03	Transfer
2	2015-11-02	Delhi	2021-03-06	Transfer
3	2020-01-01	Mumbai	2021-03-06	New
4	2007-07-30	Delhi	2021-03-04	New

I want to get data from this table where empid in (1,2,4). That will return:

empid	joindate	location	HRupdatedate	Changes
1	2002-01-05	Delhi	2021-03-01	New
2	2009-09-09	Mumbai	2021-03-05	New
1	2010-06-27	Hyderabad	2021-03-03	Transfer
2	2015-11-02	Delhi	2021-03-06	Transfer
4	2007-07-30	Delhi	2021-03-04	New

But I only need the latest record without the duplicate entries:

empid	joindate	location	HRupdatedate	Changes
1	2010-06-27	Hyderabad	2021-03-03	Transfer
2	2015-11-02	Delhi	2021-03-06	Transfer
4	2007-07-30	Delhi	2021-03-04	New

How to achieve this?

Answer 1

You can use top with ties

select top(1) with ties *
from employeetable
where empid in (1,2,4)
order by row_number() over(partition by empid order by joindate desc)

Answer 2

You can easily achieve this by using WHERE clause.

select * from  
employeetable et1
where 
    joindate = (
        select max(joindate)
            from employeetable et2 
            where et1.empid = et2.empid
    ) 
    and 
    empid in (1,2, 4);

Or for more precise results

select * from  
employeetable et1
where 
    joindate = (
        select max(joindate)
            from employeetable et2 
            where et1.empid = et2.empid
    ) 
    and 
    HRupdatedate = (
        select max(HRupdatedate)
            from employeetable et2 where et1.empid = et2.empid
    )
    and 
    empid in (1,2, 4);