Querying database inside of PHP class? - php

Question

so this is very simple.
Essentially, I'd like to connect the following class:
class mailManager{
function add($address){
$check = $db->query("SELECT * FROM mail_list WHERE email = '$address'");
$exist = mysqli_num_rows($check);
if($exist > 0){
return "Whoops! Your email is already registered with us.";
}else{
if($insert = $db->query("INSERT INTO mail_list (email, datetime) VALUES ('$address', DATE)")){
return "Success! You've joined the CSGO Earn family.";
} else {
return "Aw snap! There was a database communication error. Please try later.";
}
}
}
}
to the database.
However, nothing 'obvious' that I try seems to work and a google search has yielded no results that I can understand. Perhaps somebody could explain it simply for me?
Note: The SQL is there, but it doesn't do anything (obviously).
Regards

Answer 1

Your class does not have immediate access to your $db. You can do this a few different ways.
1) Pass $db into your public function __construct($db) and assign it to a class member like private $db; (most useful)
You then access it like $check = $this->db->query("..etc..");
2) Pass it in via a parameter to the add() function like so:
public function add($address, $db) {
}
3) Bring it in as a global variable: (easiest)
function add($address){
global $db;
$check = $db->query("SELECT * FROM mail_list WHERE email = '$address'");
/*
etc....
*/
}
I'd recommend learning how to do the first one as it will come in very handy when you have a number of database calls within your class.
Two more things regarding your code in the function.
1) You should use NOW() instead of DATE.
2) Since you are using the OOP implementation of mysqli, you should change mysqli_num_rows($check); to $check->num_rows();. I'm not sure if it will work the way you have it, but even if it does it's good practice to treat your objects uniformly.