PAVB:

Thanks for your input. Based on what you said, add partition clause can not work on unpartitioned table. So I have to create a new table with the partition I need. Am I right? These two tables have contained huge data and I don't want to truncate data and reload it again. This is why I tried to use " alter table add partition" clause. So based on this circumstance, what is the best approach to put partition on existing tables with data? Thanks in advance.