MySQL Code

[Jennitha Jungitoo]

I am a beginner in MySQL. I have this code and I would like an explanation on how the function knows which database to use since $conn and $db are defined?

$conn = mysql_connect("localhost","primeb5_mysql","***");
$db = mysql_select_db("primeb5_unigis");
$query = "SELECT * FROM lesson3";
$result = mysql_query($query);
I