SELECT S.[SAMPNO]
      ,S.[LOCCODE]
      ,S.[LOCDESCR]
      ,S.[LOGBATCH]
      ,S.[LOGUSER]
      ,S.[COLDATE]
      ,U.[Compstartdate]
      ,U.[Compstarttime]

  FROM [dbo].[SAMPLE] as S
  JOIN [dbo].[SUSERFLDS] as U
  on S.SAMPNO = U.SAMPNO

  Where
    Case
        When DATEPART(DAY, Convert(VARCHAR(10),U.Compstartdate,101)) !=
             DATEPART(DAY, DATEADD(DAY, -1, S.COLDATE))

        Then 'Yes'

        ELSE 'NO'

    END ='YES'