Re Assign Oracle Table Column Without Delete Data From Table Using (Rebuild form TOAD)

***Table ->altermode->Rebuild-> Script-> Re Assign Column -> Finally  Execute.***

--  **********************************************************************
--  Note: This rebuild script is not meant to be used when a possibility *
--        exists that someone might try to access the table while it is  *
--        being rebuilt!  If you need online table rebuilding and you    *
--        are on Oracle 10g or newer, use the dbms_redfinition wizard    *
--        under database -> optimize. (Requires DB Admin module)         *
--                                                                       *
--        Locks are released when the first DDL, COMMIT or ROLLBACK is   *
--        performed, so adding a "Lock table" command at the top of this *
--        script will not prevent others from accessing the table for    *
--        the duration of the script.                                    *
--                                                                       *
--   One more important note:                                            *
--        This script will cause the catalog in replicated environments  *
--        to become out of sync.                                         *
--  **********************************************************************

--  Table Rebuild script generated by Toad
--
--  Original table: TEST1
--  Backup of table: TEST1_X
--  Date: 11/05/2019 12:48:57