In one of my forms I use the rich text editor from Yahoo!. Now i want to store the data from that textarea in a MySQL database.
The user can enter anything in that texta
You can use mysql_real_escape_string().
Escapes special characters in the unescaped_string, taking into account the current character set of the connection so that it is safe to place it in a mysql_query(). If binary data is to be inserted, this function must be used.
mysql_real_escape_string() calls MySQL's library function mysql_real_escape_string, which prepends backslashes to the following characters: \x00, \n, \r, \, ', " and \x1a.
This function must always (with few exceptions) be used to make data safe before sending a query to MySQL.
e.g.
$value = mysql_real_escape_string(" ' \" etc ");
$sql = "INSERT INTO blah VALUES ('$value')";
But a better solution is to use PDO and prepared statements.