Connect to MySQL database using PHP OOP concept - php

Question

I'm writing a class and handful of functions to connect to the database and retrieve the information from the tables. I went through previous posts having similar titles, but most of them have written using mysql functions and I am using mysqli functions.
I want somebody who can go through this simple script and let me know where I am making my mistake.
This is my class.connect.php:
<?php
class mySQL{
var $host;
var $username;
var $password;
var $database;
public $dbc;
public function connect($set_host, $set_username, $set_password, $set_database)
{
$this->host = $set_host;
$this->username = $set_username;
$this->password = $set_password;
$this->database = $set_database;
$this->dbc = mysqli_connect($this->host, $this->username, $this->password, $this->database) or die('Error connecting to DB');
}
public function query($sql)
{
return mysqli_query($this->dbc, $sql) or die('Error querying the Database');
}
public function fetch($sql)
{
$array = mysqli_fetch_array($this->query($sql));
return $array;
}
public function close()
{
return mysqli_close($this->dbc);
}
}
?>
This is my index.php:
<?php
require_once ("class.connect.php");
$connection = new mySQL();
$connection->connect('localhost', 'myDB', 'joker', 'names_list');
$myquery = "SELECT * FROM list";
$query = $connection->query($myquery);
while($array = $connection->fetch($query))
{
echo $array['first_name'] . '<br />';
echo $array['last_name'] . '<br />';
}
$connection->close();
?>
I am getting the error saying that Error querying the Database.

Answer 1

Few problems :-
you don't die without provide a proper mysql error (and is good practice to exit gracefully)
fetch method is only FETCH the first row
mysqli have OO method, why you still using procedural function?

Answer 2

The problem is either this:
public function fetch($sql)
{
$array = mysqli_fetch_array($this->query($sql));
return $array;
}
or this:
while($array = $connection->fetch($query))
Because you are using the result from the query to query again. Basically, you are doing:
$r = mysqli_query($this->dbc, $sql);
$array = mysqli_fetch_array(mysqli_query($this->dbc, $r));
And you are getting an error, because $r is not a query string. When it's converted to a string, it's a "1" (from your other comment).
Try changing the function to (changed name of variable so you can see the difference):
public function fetch($result)
{
return mysqli_fetch_array($result);
}
or just call the function directly.

Answer 3

If you don't do your own db abstraction for learning php and mysql, you can use Medoo (http://medoo.in/).
It's a free and tiny db framework, that could save a huge work and time.

Answer 4

Obviously an error occurs on SELECT * FROM list you can use mysqli_error to find the error:
return mysqli_query($this->dbc, $sql) or die('Error:'.mysqli_error($this->dbc));
This will display the exact error message and will help you solve your problem.

Answer 5

Try to check this
https://pramodjn2.wordpress.com/
$database = new db();
$query = $database->select(‘user’);
$st = $database->result($query);
print_r($st);
class db {
public $server = ‘localhost';
public $user = ‘root';
public $passwd = ‘*****';
public $db_name = ‘DATABASE NAME';
public $dbCon;
public function __construct(){
$this->dbCon = mysqli_connect($this->server, $this->user, $this->passwd, $this->db_name);
}
public function __destruct(){
mysqli_close($this->dbCon);
}
/* insert function table name, array value
$values = array(‘first_name’ => ‘pramod’,’last_name’=> ‘jain’);
*/
public function insert($table,$values)
{
$sql = “INSERT INTO $table SET “;
$c=0;
if(!empty($values)){
foreach($values as $key=>$val){
if($c==0){
$sql .= “$key='”.htmlentities($val, ENT_QUOTES).”‘”;
}else{
$sql .= “, $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}
$c++;
}
}else{
return false;
}
$this->dbCon->query($sql) or die(mysqli_error());
return mysqli_insert_id($this->dbCon);
}
/* update function table name, array value
$values = array(‘first_name’ => ‘pramod’,’last_name’=> ‘jain’);
$condition = array(‘id’ =>5,’first_name’ => ‘pramod!’);
*/
public function update($table,$values,$condition)
{
$sql=”update $table SET “;
$c=0;
if(!empty($values)){
foreach($values as $key=>$val){
if($c==0){
$sql .= “$key='”.htmlentities($val, ENT_QUOTES).”‘”;
}else{
$sql .= “, $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}
$c++;
}
}
$k=0;
if(!empty($condition)){
foreach($condition as $key=>$val){
if($k==0){
$sql .= ” WHERE $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}else{
$sql .= ” AND $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}
$k++;
}
}else{
return false;
}
$result = $this->dbCon->query($sql) or die(mysqli_error());
return $result;
}
/* delete function table name, array value
$where = array(‘id’ =>5,’first_name’ => ‘pramod’);
*/
public function delete($table,$where)
{
$sql = “DELETE FROM $table “;
$k=0;
if(!empty($where)){
foreach($where as $key=>$val){
if($k==0){
$sql .= ” where $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}else{
$sql .= ” AND $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}
$k++;
}
}else{
return false;
}
$del = $result = $this->dbCon->query($sql) or die(mysqli_error());
if($del){
return true;
}else{
return false;
}
}
/* select function
$rows = array(‘id’,’first_name’,’last_name’);
$where = array(‘id’ =>5,’first_name’ => ‘pramod!’);
$order = array(‘id’ => ‘DESC’);
$limit = array(20,10);
*/
public function select($table, $rows = ‘*’, $where = null, $order = null, $limit = null)
{
if($rows != ‘*’){
$rows = implode(“,”,$rows);
}
$sql = ‘SELECT ‘.$rows.’ FROM ‘.$table;
if($where != null){
$k=0;
foreach($where as $key=>$val){
if($k==0){
$sql .= ” where $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}else{
$sql .= ” AND $key='”.htmlentities($val, ENT_QUOTES).”‘”;
}
$k++;
}
}
if($order != null){
foreach($order as $key=>$val){
$sql .= ” ORDER BY $key “.htmlentities($val, ENT_QUOTES).””;
}
}
if($limit != null){
$limit = implode(“,”,$limit);
$sql .= ” LIMIT $limit”;
}
$result = $this->dbCon->query($sql);
return $result;
}
public function query($sql){
$result = $this->dbCon->query($sql);
return $result;
}
public function result($result){
$row = $result->fetch_array();
$result->close();
return $row;
}
public function row($result){
$row = $result->fetch_row();
$result->close();
return $row;
}
public function numrow($result){
$row = $result->num_rows;
$result->close();
return $row;
}
}

Answer 6

The mysqli_fetch_array function in your fetch method requires two parameters which are the SQL result and the kind of array you intend to return. In my case i use MYSQLI_ASSOC.
That is it should appear like this:
public function fetch($sql)
{
$array = mysqli_fetch_array($this->query($sql), MYSQLI_ASSOC);
return $array;
}

Answer 7

**classmysql.inc.php**
<?php
class dbclass {
var $CONN;
function dbclass() { //constructor
$conn = mysql_connect(SERVER_NAME,USER_NAME,PASSWORD);
//$conn = mysql_connect(localhost,root,"","");
if(!$conn)
{ $this->error("Connection attempt failed"); }
if(!mysql_select_db(DB_NAME,$conn))
{ $this->error("Database Selection failed"); }
$this->CONN = $conn;
return true;
}
//_____________close connection____________//
function close(){
$conn = $this->CONN ;
$close = mysql_close($conn);
if(!$close){
$this->error("Close Connection Failed"); }
return true;
}
function error($text) {
$no = mysql_errno();
$msg = mysql_error();
echo "<hr><font face=verdana size=2>";
echo "<b>Custom Message :</b> $text<br><br>";
echo "<b>Error Number :</b> $no<br><br>";
echo "<b>Error Message :</b> $msg<br><br>";
echo "<hr></font>";
exit;
}
//_____________select records___________________//
function select ($sql=""){
if(empty($sql)) { return false; }
if(!eregi("^select",$sql)){
echo "Wrong Query<hr>$sql<p>";
return false; }
if(empty($this->CONN)) { return false; }
$conn = $this->CONN;
$results = #mysql_query($sql,$conn);
if((!$results) or empty($results)) { return false; }
$count = 0;
$data = array();
while ( $row = mysql_fetch_array($results)) {
$data[$count] = $row;
$count++; }
mysql_free_result($results);
return $data;
}
//________insert record__________________//
function insert ($sql=""){
if(empty($sql)) { return false; }
if(!eregi("^insert",$sql)){ return false; }
if(empty($this->CONN)){ return false; }
$conn = $this->CONN;
$results = #mysql_query($sql,$conn);
if(!$results){
$this->error("Insert Operation Failed..<hr>$sql<hr>");
return false; }
$id = mysql_insert_id();
return $id;
}
//___________edit and modify record___________________//
function edit($sql="") {
if(empty($sql)) { return false; }
if(!eregi("^update",$sql)){ return false; }
if(empty($this->CONN)){ return false; }
$conn = $this->CONN;
$results = #mysql_query($sql,$conn);
$rows = 0;
$rows = #mysql_affected_rows();
return $rows;
}
//____________generalize for all queries___________//
function sql_query($sql="") {
if(empty($sql)) { return false; }
if(empty($this->CONN)) { return false; }
$conn = $this->CONN;
$results = mysql_query($sql,$conn) or $this->error("Something wrong in query<hr>$sql<hr>");
if(!$results){
$this->error("Query went bad ! <hr>$sql<hr>");
return false; }
if(!eregi("^select",$sql)){return true; }
else {
$count = 0;
$data = array();
while ( $row = mysql_fetch_array($results))
{ $data[$count] = $row;
$count++; }
mysql_free_result($results);
return $data;
}
}
function extraqueries($sql="") {
if(empty($sql)) { return false; }
if(empty($this->CONN)) { return false; }
$conn = $this->CONN;
$results = mysql_query($sql,$conn) or $this->error("Something wrong in query<hr>$sql<hr>");
if(!$results){
$this->error("Query went bad ! <hr>$sql<hr>");
return false; }
else {
$count = 0;
$data = array();
while ( $row = mysql_fetch_array($results))
{ $data[$count] = $row;
$count++; }
mysql_free_result($results);
return $data;
}
}
}
?>
**config.inc.php**
<?php
ini_set("memory_limit","70000M");
ini_set('max_execution_time', 900);
ob_start();
session_start();
error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED);
############################################
# Database Server
############################################
if($_SERVER['HTTP_HOST']=="localhost")
{
define("DB_NAME","DB_NAME");
define("SERVER_NAME","SERVER_NAME");
define("USER_NAME","USER_NAME");
define("PASSWORD","PASSWORD");
}
else
{
define("DB_NAME","DB_NAME");
define("SERVER_NAME","SERVER_NAME");
define("USER_NAME","USER_NAME");
define("PASSWORD","PASSWORD");
}
#############################################
# File paths
#############################################
// For the Database file path
include("system/classmysql.inc.php");
//For the inc folders
define("INC","inc/");
//For the Function File of the pages folders
define("FUNC","func/");
//For the path of the system folder
define("SYSTEM","system/");
$table_prefix = 'dep_';
################################################################
# Database Class
################################################################
$obj_db = new dbclass();
?>
**Function Page**
<?php
// IF admin is not logged in
if(!isset($_SESSION['session_id']))
{
header("location:index.php");
}
$backpage = 'page.php?type=staff&';
if(isset($_REQUEST['endbtn']) && trim($_REQUEST['endbtn']) == "Back")
{
header("location:".$backpage);
die();
}
// INSERT into database.
if(isset($_REQUEST['submit']) && trim($_REQUEST['submit']) == "Submit")
{
$pass = addslashes(trim($_REQUEST['password']));
$password = encrypt($pass, "deppro");
$username = addslashes(trim($_REQUEST['username']));
$sql = "select * from ".$table_prefix."users where `UserName` ='".$username."'";
$result = $obj_db->select($sql);
if(count($result) == 0)
{
$insert="INSERT INTO ".$table_prefix."users (`UserName`)VALUES ('".$username."')";
$sql=$obj_db->insert($insert);
$newuserid = mysql_insert_id($obj_db->CONN);
}
header("location:".$backpage."msg=send&alert=2");
die();
}
// DELETE record from database
if(isset($_REQUEST['action']) && trim($_REQUEST['action'])==3)
{
if(isset($_REQUEST['id']) && trim($_REQUEST['id']!=""))
{
$id = site_Decryption($_REQUEST['id']);
$sql_del = "Delete from ".$table_prefix."users where StaffID ='$id'";
$del = $obj_db->sql_query($sql_del);
header("location:".$backpage."msg=delete&alert=2");
die();
}
}
// UPDATE the record
$action=1;
if((isset($_REQUEST['action']) && trim($_REQUEST['action'])==2) && (!(isset($_REQUEST['submit']) && trim($_REQUEST['submit']) == "Submit")))
{
if(isset($_REQUEST['id']) && trim($_REQUEST['id']!=""))
{
$id = site_Decryption($_REQUEST['id']);
//$id = $_SESSION['depadmin_id'];
$sql = "select * from ".$table_prefix."users where StaffID ='$id'";
$result = $obj_db->select($sql);
if($result)
{
foreach($result as $row)
{
$title = stripslashes($row['StaffTitle']);
$action=2;
}
}
if(isset($_REQUEST['submit']) && trim($_REQUEST['submit']) == "Update")
{
$title = addslashes(trim($_REQUEST['title']));
$sql_upd ="UPDATE ".$table_prefix."users SET `StaffTitle` = '$title' WHERE StaffID ='$id'";
$result = $obj_db->sql_query($sql_upd);
$action=1;
header("location:".$backpage."msg=edited&alert=2");
die();
}
}
}
if(isset($_REQUEST['vid']) && trim($_REQUEST['vid']!=""))
{
$id = site_Decryption($_REQUEST['vid']);
$sql = "select * from ".$table_prefix."users where StaffID ='$id'";
$result = $obj_db->select($sql);
if($result)
{
foreach($result as $row)
{
$username = stripslashes($row['UserName']);
}
}
}
?>
<td class="center"><span class="editbutton"> </span> <span class="deletebutton"> </span> <a class="lightbox" title="View" href="cpropertyview.php?script=view&vid=<?php echo site_Encryption($sql[$j]['PropertyID']); ?>&lightbox[width]=55p&lightbox[height]=60p"><span class="viewbutton"> </span></a></td>