create table oldtable
(
fileNo varchar(10),
folder varchar(10),
fileType varchar(10),
col_1 varchar(10),
col_2 varchar(10),
col_3 varchar(10),
col_4 varchar(10)
)

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('ABC' , 'Folder1','Type1' ,'111' ,'111','111' ,null)

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('ABC' , 'Folder1','Type2' ,'111' ,'111','111',null)

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('GHI' , 'Folder3','Type3' ,'333' ,'333','333','333')

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('JKL' , 'Folder4','Type3' ,'444' ,'444','444','444')

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('MNO' , 'Folder5','Type4' ,'555' ,'555' ,'555' ,'555')

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('PQR' , 'Folder6','Type4' ,'666' ,'666' ,'666' ,'666')

INSERT INTO oldtable (fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4 ) VALUES ('STU' , 'Folder7','Type5' ,'777' ,'777','777','777')

create table newtable
(
fileNo varchar(10),
folder varchar(10),
fileType varchar(10),
col_1 varchar(10),
col_2 varchar(10),
col_3 varchar(10),
col_4 varchar(10),
nid int
)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('ABC' , 'Folder1', null ,'111' ,'111','111' ,null, 1)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('ABC' , 'Folder1', null,'111' ,'111','111',null, 2)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('GHI' , 'Folder3', null ,'333' ,'333','333','333', 3)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('JKL' , 'Folder4',null ,'444' ,'444','444','444', 4)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('MNO' , 'Folder5',null ,'555' ,'555' ,'555' ,'555', 5)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('PQR' , 'Folder6',null ,'666' ,'666' ,'666' ,'666', 6)

INSERT INTO newtable(fileNo , folder, fileType, COL_1 ,COL_2 ,COL_3 ,COL_4, NID ) VALUES ('STU' , 'Folder7',null ,'777' ,'777','777','777', 7)

update 
  ( with 
      oldt as
      ( select fileNo , folder, fileType,
               row_number() over (partition by fileNo , folder
                                  order by fileType)
                 as rn
        from oldtable
      ),
    newt as
      ( select fileNo , folder, fileType, nid,
               row_number() over (partition by fileNo , folder  
                                  order by fileType)
                 as rn
        from newtable
      ),
    upd as
      ( select 
            n.nid,
            o.fileType as old_fileType
        from newt n
          join oldt o
          on  n.fileNo = o.fileNo
          and n.folder = o.folder
          and n.rn     = o.rn 
      ) 
    select 
        up.fileType,
        ( select upd.old_fileType
          from upd 
          where upd.nid = up.nid 
        ) as old_fileType
    from newtable up
  ) x
set fileType = old_fileType 

select *
from newtable