check to see if username exists

[Mr_Chew]

I have a signup page to register. What type of mysql query/php code would I use to check and see if a username already exists in the database and for that person to go back and specify a different username.

Also, what kind of code would be used if i were to have 2 password text boxes to double-check that they match?

[sab]

if ($pass != $confirmpass)
{
 print "password doesn't match";
}


$usercheck = mysql_query("select * from member where user=$username");
if ($usercheck)
{
 print "username already regisered";
}

i think this will work, i'm not sure though.