adding users points to db

Question

I did search this but can't find any thing or I'm blind.

I'm trying to add points for ever users I use update, but it keeps changing the points: for exp:

$sql = mysql_query("UPDATE users SET points='20' WHERE username='".$_SESSION['username']."'")

It adds 20 points but when I submit It again It stays the same.

Any help would be great.

Answer 1

Should probably be points=points+20