SQL for update rows of a table from another table

MERGE INTO BOARD_RESULT_DATA D --updated table
   USING (select * from SCRUTINY) S -- Source Table
   ON (D.ROLL_NO = S.ROLL_NO AND D.REGNO=s.REGNO and d.BOARD_NAME = = S.BOARD_NAME)
   WHEN MATCHED THEN UPDATE SET D.GPA = S.GPA,D.LTRGRD=S.LTRGRD,D.RESULT = S.RESULT,D.RES_DETAIL = S.RES_DETAIL,D.RES_MAIL = S.RES_DETAIL;