Without further information, what it is that you want to do and that doesn't work, it is hard to help you; nevertheless a few remarks:

After you ran this CREATE IF NOT EXISTS statement, the table will exist, if there wasn't an error. See perldoc DBI for error-reporting and -handling

You can then INSERT, UPDATE, DELETE as you like; maybe REPLACE is what you're looking for...but have a closer look on the searchable html docs with comments if you're using MySQL

regards,
tomte