OOP db connect

[city_coder]

Hi guys

im currently stood opposite a brick wall banging my head against it with this.

Iv been trying to learn the OOP way to connect to my db. Its finally got to me that i need to learn it rather than do procedural & its starting to cause me more pain than i think its worth.

Iv been looking around the web for days & trying loads of different tutorials on how to connect to my db & query it. So far iv found classes that are amazingly complex but then dont tell you how to use it, scripts that just dont work & some in the middle that just dont seem to work for me.

If anyone can just show a basic example of how to connect, close & a simple method (function, whatever you want to call it) that queries the db & the code for retrieving the query results, then i would be extremely happy!

I am one of these guys that learns by getting an example working & picking at it & changing it to suit me, then i become more confident & can start to write my own.

Cheers in advance guys.

[traq]

well, if you don't know how to code it procedurally, you'll have a hard time using OOP.

**These are basic examples and are UNTESTED**

for example, using procedural coding:

<?php 
// connect to mysql
mysql_connect("server", "user", "pass") or die(mysql_error()); 
echo 'Connected to MySQL.';

// select database
mysql_select_db("db_name") or die(mysql_error());
echo "Connected to Database";

// query
$SQL = ''; // put your SQL query here
$result = mysql_query($SQL);
while($row = mysql_fetch_array($result)){
    // do stuff with results
}

Object-oriented example:

class DB{

    // declare class variables
    private $server;
    private $user;
    private $pass;
    private $dbname;
    private $dbhandle;

    // this function builds the $DB object
    // call: $DB = new DB('server', 'user', 'pass', 'dbname');
    function __construct($server, $user, $pass, $dbname){
        
        // assign the values you're using to the class variables
        $this->server = $server;
        &this->user = $user;
        $this->pass = $pass;
        $this->dbname = $dbname;
        
        // try to connect
        $this->connect();
    }
    
    // this function makes the mysql connection
    function connect(){
        try{
            // assign mysql connection to class variable; if successful
            if($this->dbhandle = mysql_connect($this->server, $this->user, $this->pass)){
                // try to select DB
                if(mysql_select_db($this->dbname)){
                    return TRUE;
                }else{
                    // this is the error if mysql_select_db() fails
                    throw new Exception(mysql_error());
                }
            }else{ 
                // this is the error if mysql_connect() fails
                throw new Exception(mysql_error()); 
            }
        }catch(Exception $e){
            // show any errors
            echo 'MySQL error: '.$e->getMessage();
            return FALSE;
        }
    }
    
    // this function performs a query
    // call: $DB->query("SQL statement");
    function query($SQL){
        // check if the db handle is working and try to reconnect if not
        if(!$this->dbhandle){ $this->connect(); }
        
        // perform query
        try{
            if($result = mysql_query($SQL)){ 
                return $result;
                // optionally, you could call another function to process results
                // e.g., something like "$this->printresults();"
            }else{
                throw new Exception(mysql_error());
            }
        }catch(Exception $e){
            echo 'Error in query; '.$e->getMessage();
            return FALSE;
        }
        
    }

} 

as you can see, OO is a lot more overhead. it's useful if you're going to be doing the same thing over and over: a class is basically a collection of related functions and results that you can use. if you're learning, or only doing a few queries, do it procedurally.