Reusing a mysql connection in oop php [duplicate] - php

Question

This question already has answers here:
Use global variables in a class
(4 answers)
Closed 7 years ago.
Solution taken from comment so I can't accept an answer for this to be closed. But I did post the actual solution that works for me below
I'm new to OOP and I just can't figure out, even after reading through quite few examples, how use the same mysql connection without using $GLOBALS.
If someone can explain it like I'm a two year old that would be super helpful.
This is my connection file.
$hostname = 'hostname';
$username = 'db';
$password = 'password';
try {
$dbh = new PDO("mysql:host=$hostname;dbname=db", $username, $password);
}
catch(PDOException $e)
{
echo $e->getMessage();
}
but then to use this in a class or a function I do this:
class basic {
function simple($id) {
$query = $GLOBALS['dbh']->query("SELECT * FROM table WHERE id = $id");
$row = $query->fetch(PDO::FETCH_OBJ);
$thing = $row->partoftable;
echo $thing;
}
}
$first = new basic();
$first->simple(12);
This of course will return what I'm looking for the $thing with the id of 12. But how do I do this without the GLOBALS['dbh'] to connect to the db?
Also feel free to rip anything else apart but just keep in mind this was the easiest example of what I'm talking about.
Thanks in advance.
This is the solution that works for me based on the comment below.
class basic {
function __construct($dbh)
{
$this->dbh = $dbh;
}
function simple($id) {
$query = $this->dbh->query("SELECT * FROM table WHERE id = $id");
$row = $query->fetch(PDO::FETCH_OBJ);
$thing = $row->partoftable;
echo $thing;
}
}
$first = new basic($dbh);
$first->simple(12);
Thanks. hope this helps someone else.

Answer 1

class basic {
var $CONNECTION;
function __construct($dbh) {
$this->CONNECTION = $dbh;
}
function simple($id) {
$conn = $this->CONNECTION;
$query = $conn->prepare("SELECT * FROM table WHERE id = $id");
$query->execute();
$row = $query->fetch(PDO::FETCH_OBJ);
$thing = $row->partoftable;
echo $thing;
}
}
//class ends you can use thae class like this
$hostname = 'hostname';
$username = 'db';
$password = 'password';
try {
$dbh = new PDO("mysql:host=$hostname;dbname=db", $username, $password);
}
catch(PDOException $e)
{
echo $e->getMessage();
}
$first = new basic($dbh);
$first->simple(12);

Answer 2

You can create a class for database connection :
class MysqlDB
{
private $conn;
public function __construct($hostName, $userName, $passWord, $databaseName)
{
$this->conn = new PDO("mysql:host=$hostName;dbname=$databaseName", $userName, $passWord);
}
public function query($id)
{
//This is just a sample query
$this->conn->query("SELECT * FROM table WHERE id = $id");
return $query->fetch(PDO::FETCH_OBJ);
}
}
And then you can use in another class like:
class basic {
private $dbConn;
function __construct(){
$dbConn = new MysqlDB('hostName', 'username', 'password', 'database')
}
function simple($id) {
$row = $dbConn->query($id);
$thing = $row->partoftable;
echo $thing;
}
}
You can also create a database connection in common class and extend it with you class

Answer 3

I like this solution:
class db_connection
{
public static $sql_object = NULL;
public function __construct()
{
if ($sql_object === NULL)
{
// Initialize self::$sql_object
}
}
}
Then you can use it with:
$db = new db_connection();
// Do something with $db->sql_object
Since $sql_object is static, it will be initialized only once, no matter how many times you use new db_connection().

Answer 4

<?php
define('DB_SERVER','localhost');
define('DB_USER','root');
define('DB_PASS' ,'');
define('DB_NAME', 'db');
class DB_con {
function __construct()
{
$conn = mysql_connect(DB_SERVER,DB_USER,DB_PASS) or die('localhost connection problem'.mysql_error());
mysql_select_db(DB_NAME, $conn);
}
public function insert($fname,$lname,)
{
$res = mysql_query("INSERT users(first_name,last_name,) VALUES('$fname','$lname')");
return $res;
}
public function select($id)
{
$res=mysql_query("SELECT * FROM users WHERE id = $id");
return $res;
}
} ?>