如何使用RMySQL包更新MySQL表

Instead of append or overwrite an entire table to database, is there any function in RMySQL that can update only part of the table? Because some of our data could be imcomplete someday, that I need to remain the old table and only replace the rows that has new data coming in, here is the function I wrote, but did not work, any help would be appreciated:Instead of append or overwrite an entire table