Android - How to avoid repetition of values before inserting in SqliteDB?

In my app, i am supposed to log values for all days of the week..Sat,sun,mon etc and i am supposed to plot values in a graph to show some statistics..So while logging, if i have already logged for that day of the week previously, how do i dele开发者_如何学Pythonte it ?and then log new values?

Check if it is allready created and if it is, then use UPDATE to overwrite the new data :-)