PHP: what is wrong with this query? username database

I am trying to make a page where people can register to be users on my site. the connection is fine (labled as $cxn here) so the problem must be with the query. I've tried typing in queries with the exact same syntax into mySQL, so I must have some problem with the PHP here. can someone help me out?

Also, the part that shows the mysqli_error isn't working for some reason either.

//the variables
	$username = $_GET['username'];
	$password = $_GET['password'];
	$email = $_GET['email'];
	$first = $_GET['firstname'];
	$last = $_GET['lastname'];
	$date = date("Y-m-d");
	//checks to make sure username isn't taken
	$query = "Select * from $t_user WHERE username = $username";
	$result = mysqli_query($query,$cxn);
	if($result){
		echo "Username is already taken!";
		$_GET = null;
		echo "<a href=\"register.php\"> Try Again? </a>";	
	}
	//adds them to database.
	else{
		$query = "INSERT INTO users (username, password, email, first_name, last_name, create_date) VALUES ('$username', '$password', '$email', '$first', '$last', '$date')";	
		$result = mysqli_query($query,$cxn); 
		if($result){
			echo "Welcome to Athens Bar Hopper!";	
		}
		else{
			echo "my bad, something didn't go right";
			$problem =  mysqli_error($cxn);
			echo $problem;
		}
	}	

PHP:

 

//the variables
    $username = $_GET['username'];
    $password = $_GET['password'];
    $email = $_GET['email'];
    $first = $_GET['firstname'];
    $last = $_GET['lastname'];
    $date = date("Y-m-d");
    //checks to make sure username isn't taken
    $query = "Select * from $t_user WHERE username = $username";
    $result = mysqli_query($cxn,$query);
    if($result){
        echo "Username is already taken!";
        $_GET = null;
        echo "<a href=\"register.php\"> Try Again? </a>";   
    }
    //adds them to database.
    else{
        $query = "INSERT INTO users (username, password, email, first_name, last_name, create_date) VALUES ('$username', '$password', '$email', '$first', '$last', '$date')";   
        $result = mysqli_query($query,$cxn);
        if($result){
            echo "Welcome to Athens Bar Hopper!";   
        }
        else{
            echo "my bad, something didn't go right";
            $problem =  mysqli_error($cxn);
            echo $problem;
        }
    }

PHP:

 

give the mysqli errors if not working

 

Try adding some escaped quotes around $username like:
WHERE username = \"$username\"";

So the whole query looks like:
$query = "Select * from $t_user WHERE username = \"$username\"";

By the way, is the Georgia Bar still there?

 

...
ok, I really don't understand some of the people in the forum anymore.
cornetofreak, so spend one post just quoting my code, and another telling me to use mysqli_error, when I already said:

in my first post, and in the code there is a call to the mysqli_error function.

Karin, thanks for pointing out that typo. but the problem is that when I fill out all of the forums correctly, it still will not execute the INSERT query, and I don't know why.

oh, and Georgia Bar is still there.

 

It looks like he made a slight modification to your code :
$result = mysqli_query($cxn,$query);

And he was asking for the error message, not asking to you to use it.
My only question would be, did you mean to use a variable to select the table (it isn't defined in what you posted).
$query = "Select * from $t_user WHERE username = $username";