text: -- add not null constraints for SYS_CONFIG
  
  drop index IDX_SYS_CONFIG_UNIQ_NAME^
  
  begin
     execute immediate 'alter table SYS_CONFIG modify NAME not null';
     execute immediate 'alter table SYS_CONFIG modify VALUE_ not null';
  exception
      when others then
          null;
  end;
  ^
  
  create index IDX_SYS_CONFIG_UNIQ_NAME on SYS_CONFIG (NAME)^