Error message: Database Query failed - php

Question

For some reason, the following code inside the query works in my MySQL command console, yet when I try to run it as a Query in PHP, something keeps going wrong and I'm not sure what. Here is the code I've done so far.
//2. Perform database query
$query = "SELECT skills.element_id, content_model_reference.element_id, element_name FROM skills, content_model_reference WHERE (skills.element_id = content_model_reference.element_id)";
$result = mysql_query($query);
//Tests if there was a query error
if(!$result){
die("Database query failed.");
}
Is there something preventing the code that worked in MySQL (The line with SELECT) from working, or is my syntax somehow wrong?
EDIT: So it's saying I didn't select a database. Yet I thought I had. Here is the code above it:
//1. Create a database connection
$dbhost = "host"; //Host: Can be either an IP address, or a domain (like google.com).
$dbuser = "user";//User: The user that is connecting to the database.
$dbpass = "pass";//Password: This is the password that the user is using.
$dbname = "db";//Name: This is the name of the database.
$connection = mysqli_connect($dbhost, $dbuser, $dbpass, $dbname);//The value, 'handle,' is the connection.
//Test if connection occurred. Die ends the program/php, and in this case, also prints a message
if(mysqli_connect_errno()){
die("Database connection failed: ".
mysqli_connect_error().
" (". mysqli_connect_errno() . ")"
);
}
Like I said, the error message I am getting is pertaining only to the query, the server is fine with my database connection.

Answer 1

You're using mysqli_* for the connection, but you're using mysql_* for the QUERY... don't think you can do that, has to be one or the other (MYSQLI_ preffered). Also the query should be:
$result = mysqli_query($connection,$query);