[mysql] MySQL - UPDATE query based on SELECT Query

I had an issue with duplicate entries in one table itself. Below is the approaches were working for me. It has also been advocated by @sibaz.

Finally I solved it using the below queries:

  1. The select query is saved in a temp table

    IF OBJECT_ID(N'tempdb..#New_format_donor_temp', N'U') IS NOT NULL
        DROP TABLE #New_format_donor_temp;
    
    select *
    into #New_format_donor_temp
    from DONOR_EMPLOYMENTS
    where DONOR_ID IN (
      1, 2
    )
    
    -- Test New_format_donor_temp
    -- SELECT *
    -- FROM #New_format_donor_temp;
    
  2. The temp table is joined in the update query.

    UPDATE de
    SET STATUS_CD=de_new.STATUS_CD, STATUS_REASON_CD=de_new.STATUS_REASON_CD, TYPE_CD=de_new.TYPE_CD
    FROM DONOR_EMPLOYMENTS AS de
      INNER JOIN #New_format_donor_temp AS de_new ON de_new.EMP_NO = de.EMP_NO
    WHERE
      de.DONOR_ID IN (
        3, 4
    )
    

I not very experienced with SQL please advise any better approach you know.

Above queries are for MySql server.

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