Setting up a database connection class in PHP - php

Question

I was recently introduced to the idea of classes in PHP, and after some research I've come to the conclusion that I need to store database related functions in a class to access later. It has worked for the most part, but some use cases I am still confused with. For example,
Below is an example of how I would normally connect to my database and display information from user id's in a table
dbcon.php:
<?php
$con = mysqli_connect("host","username","password","database") or die("Couldn't connect");
require_once("functions.php");
?>
functions.php
function getUserInfo($id) {
$query = mysqli_query($con, "SELECT * FROM users WHERE id = '$id'");
return mysqli_fetch_array($query);
}
Some random file:
require_once("dbcon.php");
$result = mysqli_query($con, "SELECT * FROM tablename");
while ($row = mysqli_fetch_assoc($result)) {
$userinfo = getUserInfo($row['userid']);
echo $userinfo['name'];
}
?>
I don't feel like this method of querying the database and displaying information is the neatest or most efficient way possible. I read this article about using classes to tamper with a database and call functions that I created in the class.
My first question is this: When I try to access $con in functions.php, it is undefined. How can I pass the variable from dbcon.php to functions.php over the require_once function?
I also would like to know what the best way to store my connection to the database is, and if there are any tutorials on how to set that up.
I hope you understood that lol.

Answer 1

You can do it like this way:-
Dbconnection.php:-
<?php
Class DbConnection{
function getdbconnect(){
$conn = mysqli_connect("host","username","password","database") or die("Couldn't connect");
return $conn;
}
}
?>
Function.php:-
<?php
require_once('Dbconnection.php');
Class WorkingExamples{
function getUserInfo($id) {
$Dbobj = new DbConnection();
$query = mysqli_query($Dbobj->getdbconnect(), "SELECT * FROM users WHERE id = '$id'");
return mysqli_fetch_array($query);
}
}
$data = new WorkingExamples();
echo "<pre/>";print_r($data->getUserInfo(3));
?>
Note:- this is an example, try it by changing values according to your requirement and get the result.

Answer 2

<?php
class DatabaseConnection
{
private $host = "127.0.0.1";
private $dbname = "online_english";
private $dbUsername = "root";
private $dbPass = "";
private $charset = 'utf8mb4';
private $dsn;
public function tryConnect(){
try{
$this->dsn = "mysql:host=$this->host;dbname=$this->dbname;charset=$this->charset";
$DBH = new PDO($this->dsn,$this->dbUsername,$this->dbPass);
$DBH->exec("set names utf8");
$DBH->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
return $DBH;
}
catch (PDOException $e){
$e->getMessage();
}
}
}
?>

Answer 3

<?php
class Database{
const DB_HOSTNAME = 'localhost';
const DB_USERNAME = 'root';
const DB_PASSWORD = 'root';
const DB_NAME = 'stockganesha';
public $_db_connect;
protected $_sql;
protected $_result;
protected $_row;
function db_connect(){
$this->_db_connect = mysqli_connect(self::DB_HOSTNAME,self::DB_USERNAME,self::DB_PASSWORD,self::DB_NAME) or die(mysql_error());
return $this->_db_connect;
}
function sql(){
$this->_sql = 'SELECT * FROM customers';
}
function query(){
$this->_result = mysqli_query($this->_db_connect,$this->_sql);
}
function fetch_array(){
while($this->_row = mysqli_fetch_array($this->_result)){
$username = $this->_row['first_name'];
echo "<ul>";
echo "<li>".$username."</li>";
echo "</ul>";
}
}
function db_close(){
mysqli_close($this->_db_connect);
}
}
and Import this in another class
<?php
require_once('../Config/Dbconnection.php');
include './model.php';
class CustomerDTO{
private $mysql;
function __construct() {
$database = new Database();
$this->mysql = $database->db_connect();
}
function create($customer){
$firstName = $customer->getFirstName();
$lastName = $customer->getLastName();
$emailId = $customer->getEmailId();
$mobileNumber = $customer->getMobileNumber();
$dateOfBirth = $customer->getDateOfBirth();
$phoneNumber = $customer->getPhoneNumber();
$termAndCondtion = $customer->getTermAndCondition();
$result = mysqli_query($this->mysql, "Insert into customers (first_name,last_name,email_id,mobile_number,date_of_birth,phone_number,term_and_condition)
values('$firstName','$lastName','$emailId','$mobileNumber','$dateOfBirth','$phoneNumber','$termAndCondtion')");
return $result;
}
function read(){
$result = mysqli_query( $this->mysql, "Select * from customers");
return $result;
}
function update($id, $customer){
$result = mysqli_query($this->mysql, "update customers set
first_name = ".$customer->getFirstName()."
last_name = ".$customer->getLastName()."
email_id = ".$customer->getEmailId()."
mobile_number = ".$customer->getMobileNumber()."
date_of_birth = ".$customer->getDateOfBirth()."
phone_number = ".$customer->getPhoneNumber()."
term_and_condition = ".$customer->getTermAndCondition()."
where id = ".$customer->getId());
return $result;
}
public function delete($id){
$result = mysqli_query($this->mysql, "delete from customers where id =".$id);
return $result;
}
}