Slow update query

I want to update table by using another table columns. I wrote the update query like as below. But it takes an hour and not finished. All table structure is similar and similar size (220000 records for each). How can optimize the query or is there any other solution for making this update

  UPDATE CELLCFG.NEIGHBOUR_LIST N1
  SET
(CAND, CS, KHYST, KOFFSETP, LHYST, LOFFSETP, TRHYST, TROFFSETP, AWOFFSET, BQOFFSET)=
 (SELECT N2.CAND, N2.CS, N2.KHYST, N2.KOFFSET, N2.LHYST, N2.LOFFSET,          N2.TRHYST, N2.TROFFSET, N2.AWOFFSET, N2.BQOFFSET   FROM CELLTRANSFORM.NEIGHBOUR_LIST
  WHERE N1.MAIN_CELL_KEY=N2.MAINKEY
  AND N1.NEIGHBOUR_CELL_KEY=N2.NBRKEY); BR

Tayfun Received on Tue Mar 16 2004 - 06:45:03 CST