How prevent hack database

Yes of course
My app is competition with score
In this app,all user add code in app and if code is exist in database,so we give score for user
And in end,for users who have high score,we give gift(iphone) for his/him
This code inserted in database about 1 million records
Now if hacker hack my database and can get all code,so he/she can give all code for user and we will go away
Is it enough?

possible attack vectors:
- sql injection
- employee
- hoster
- bad server config (e.g the db server can be accessed from the outside)
- server not uptodate
etc.

- only write access to the table. If you need to read, create an other user.
- the databaseserver should be not accessed from the outside
- server uptodate
- important: ask an expert for help

i am not a security expert.

Very good point
Thanks