can't write strings to database

[eluser]CroNiX[/eluser]
Don't strings need to be quoted going into the database? Yours isn't. Numbers don't need to be, so that's why they work ok.

You're also not escaping your variables, which is not good and leaves you open to SQL injection. Always escape variables on manual query, or better yet, use Active Record or query bindings which escapes all variables automatically. A hacker could easily change your query string, just sitting there openly in the url, and enter some SQL commands there and your code would execute it blindly and they could take your site over, get a list of users/passwords, or whatever. Not good.