Sqlite update query error

I want to add something into every row in a column, however I have some difficulties with it. There are already some data in the rows, and I don't want to lose those, just add this new one. Table name is GroupList Column name is Commands

In the rows of commands data is seperated by a comma.

Here is my mess:

UPDATE GroupList SET Commands = ',stats.highscores', WHERE Commands != ',stats.highscores'

The , before the stats.highscores is a must. I have no idea why it won't work. I tried looking up the error code in google, but I still get the same error.

Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [mozIStorageConnection.createStatement]

I would really appriciate some help with this. Sorry if I wrote something stupid, I'm new with sqlite.

Thanks in advance:)