To find max effdt from a table

Question

i am facing problem in finding max effdt for every employee from a table.
i have to fetch emplid's from a table according to a particular deptid but there are many entries for a employee depending on effdt.I have to fetch the entry which is of max effdt.
i wrote query like dis,is it ok?
select emplid,effdt from ps_job where deptid='10000' and effdt in (select max(effdt) from ps_job group by emplid)

Answer 1

You need to correlate the effdt and the empid is some fashion There are a few ways to do this. The closest correct way to what you have is:
SELECT emplid, effdt
FROM ps_job o
WHERE deptid='10000' and
      effdt IN (SELECT MAX(effdt) FROM ps_job i
                WHERE i.emplid = o.emplid)A one-pass method, assuming you can use analytics would be:
SELECT emplid, effdt
FROM (SELECT emplid, effdt, deptid,
             ROW_NUMBER() OVER(PARTITION BY emplid
                               ORDER BY effdt DESC) rn
      FROM ps_job o)
WHERE deptid='10000' and
      rn = 1John