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Editorial Team
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Asked: 2026-05-13T14:56:50+00:00

I have a table like this userid visitorid time 1 10 2009-12-23 1 18

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I have a table like this

userid  visitorid   time
1       10          2009-12-23
1       18          2009-12-06
1       18          2009-12-14
1       18          2009-12-18
1705    1678        2010-01-24
1705    1699        2010-01-24
1705    1700        2010-01-24
1712    1           2010-01-25
1712    640         2010-01-24
1712    925         2010-01-25
1712    1600        2010-01-24
1712    1630        2010-01-25
1712    1630        2010-01-24
1713    1           2010-01-24
1713    1           2010-01-23

I would like to perform a query such that it removes all the duplicates except for the latest one. I Hope you get an idea?

Example, after the query the table must be like this

userid  visitorid   time
1       10          2009-12-23
1       18          2009-12-18
1705    1678        2010-01-24
1705    1699        2010-01-24
1705    1700        2010-01-24
1712    1           2010-01-25
1712    640         2010-01-24
1712    925         2010-01-25
1712    1600        2010-01-24
1712    1630        2010-01-25
1713    1           2010-01-24
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1 Answer

  1. Editorial Team
    Delete from YourTable VersionA
  where VersionA.Time NOT IN
    ( select MAX( VersionB.Time ) Time
         from YourTable VersionB
         where VersionA.UserID = VersionB.UserID
           and VersionA.VisitorID = VersionB.VisitorID )

    Syntax might need to be adjusted, but SHOULD do the trick. Additionally, you may want to pre-query the Subselect into its own table FIRST, then run the DELETE FROM against that result set.

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