Code Review Request

[PHPwannaB]

Hi All,

 

I'm trying to brush up on my back-end development skills and wrote these small classes to deal with modifying and retrieving data from a mySQL database. Would anyone mind taking the time to look over this code and let me know if I'm following sane programming practices or if need to completely rethink my approach?

 

File: DB.php

<?php
    include("connection-vals.inc.php");
    
    class DB {          
          public function validateUserInput($input){
            $this->connect();
            
            if(is_array($input)) {
                $inputString = mysql_escape_string(implode("#.!.#", $input));
                $input =  explode("#.!.#", $inputString);                
            } else {
                $input = mysql_escape_string($input);
            }
            
            $this->close();
            
            return $input;
        }
                
        protected $connectionID = False;        
        
        protected function connect(){
            $this->connectionID = mysql_connect(
                $this->host,
                $this->user,
                $this->pw
            ) or die($this->showError(mysql_error()));
            
            mysql_select_db(SELECTED_DB, $this->connectionID)
            or die($this->showError(mysql_error()));
        }       
        
        protected function close(){
            mysql_close($this->connectionID);
        }              
        
        protected function showError ($msg){
            echo "<p><strong>DB Error: </strong>$msg</p>";
        }   
        
        private $host = HOST;
        private $user = USER;
        private $pw = PASSWORD;             
    }
?>

 

File: DBFetcher.php

<?php
    include("db.php");
    
    class DBFetcher extends DB{
        public function fetchDataAsXML($query){
            $this->connect();            
            $response = mysql_query($query, $this->connectionID);            
            $this->close();
            
            if($response) {
                header("Content-type: text/xml");
                return $this->convertResponseToXML($response);
            } else {
                header("Content-type: text/html");
                $this->showError("No Response from the DB. Is your query well-formed?");
                return false;
            } 
        }
        
        private function convertResponseToXML($response){            
            $result = "";
            $result = $result . "<response>";
            
            while($row = mysql_fetch_assoc($response)){
                $result = $result . "<row>";
                foreach($row as $key => $value){
                    $result = $result . "<" . $key . ">" . $value . "</" . $key . ">";
                }
                $result = $result . "</row>";
            }
            
            $result = $result . "</response>";
            return $result;
        }
    }
?>

 

File: DBModifier.php

<?php
    include("db.php");

    class DBModifier extends DB{                
        public function modify($query){
            $this->connect();
            
            $response = mysql_query($query, $this->connectionID);
            
            $this->close();
            
            if($response) {
                return true;
            } else {
                $this->showError("Unable to update the DB. Is your query well-formed?");
                return false;
            }            
        }
    }
?>

Any help at all would be greatly appreciated!