Remove Duplicates

I am trying to remove duplicates from a table. Not all the students have duplicates though. I will provide 2 scenarios below: Any sugestions? I am using this query but it just removes the duplicate ids. I need more logic based on status and year.

          FROM  ##temp_test
          WHERE ##temp_test.%%physloc%%
          NOT IN (SELECT MIN(##temp_test.%%physloc%%)
           FROM   ##temp_test 
           GROUP BY id)

The first scenario I would want the record that has STATUS = Final AND the most recent YEAR. (This is the 3rd record of id 1)

The second scenario since there IS NO Final I just will take the record with the most recent YEAR (This is the second record of id 2)

  Scenario 1
  1   Joe   Math  Final   2010
  1   Joe   Math  Initial 2010
  1   Joe   Math  Final   2011
  Scenario 2
  2   Bob   Eng   Initial 2011
  2   Bob   Eng   Initial  2010

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asked May 04, 2012 at 05:12 PM in Default

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sqlLearner 1
972 39 51 57

Just to clarify, what about the scenario

 3   Kev   Physics   Initial 2010
 3   Kev   Physics   Final   2010
 3   Kev   Physics   Initial 2011

should that give you the 2nd record (as it is a Final) or the 3rd record (as that is from the latest year)?

May 04, 2012 at 05:22 PM Kev Riley ♦♦

Initial 2011..Year takes precedence over status

May 04, 2012 at 05:59 PM sqlLearner 1
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2 answers: sort voted first

This example shows how to use row_number() to rank based on various criteria. I partition each id, and then order descending by year first (as you stated it has precedence) and then order descending by a calculated value that is either 1 if the status is 'Final' or 0 otherwise.

I then choose the row number 1's from that data set and I've eliminated the dupes.

 declare @temp_test table (
     id int,
     name varchar(10),
     Class varchar(10),
     status varchar(10),
     [Year] int)
 insert into @temp_test select 1,'Joe','Math','Final',2010
 insert into @temp_test select 1,'Joe','Math','Initial',2010
 insert into @temp_test select 1,'Joe','Math','Final',2011
 insert into @temp_test select 2,'Bob','Eng','Initial',2011
 insert into @temp_test select 2,'Bob','Eng','Initial',2010
 insert into @temp_test select 3,'Kev','Physics','Initial',2010
 insert into @temp_test select 3,'Kev','Physics','Final',2010
 insert into @temp_test select 3,'Kev','Physics','Initial',2011
 select *
 from (
      rn=row_number()over(partition by id order by year desc, 
                             case when [status] = 'Final' then 1 else 0 end desc)
     from @temp_test
 where a.rn = 1
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answered May 04, 2012 at 08:10 PM

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Kev Riley ♦♦
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You can also use this solution to delete the duplicates:

 ;WITH cte
 SELECT *, ROW_NUMBER() OVER(PARTITION BY col1, col2 ORDER BY colN) AS rowcnt FROM yourtable
 --remove this comment mark if you want the deleted records to end up in an archive table
 INTO myArchive(col1,col2,colN )
 WHERE rowcnt >1

Read more at this question:


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answered Oct 10, 2012 at 07:19 AM

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Håkan Winther
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asked: May 04, 2012 at 05:12 PM

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Last Updated: Oct 10, 2012 at 07:19 AM

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