Some tips on my class?

[DigiRev]

I am writing this merely as practice for writing a PHP class. I also have a friend I program with who has a hard time with queries/databases and PHP in general, so I was hoping this might make it easier for him and also keep code neater.

I am no PHP expert yet, so I am expecting there to be quite a few things that could be improved. I haven't completed the class yet, but wanted some opinions on it before I go further...in case I am doing something very wrong.

Anyway, I'm sure there are many other much better Database classes out there, but this is the code I have, followed by an example of how it is used.

Harsh criticism is welcome.

cls_database.php:

<?php

  /* ---------------------------------------------------- /*
  - clsDatabase - cls_database.php
  - Author: Daniel Elkins
  - Purpose: First class I've ever written. For personal
  -          purposes...to make my life easier. :)
  - Copyright: (c) 2008 Daniel Elkins | All Rights Reserved
  /* ---------------------------------------------------- */
  
  class Database {
    
    var $host;
    var $username;
    var $password;
    var $db_name;
    var $dbc;
    var $error_mode = 0;
    var $table;
    var $result_set;
    var $record_count;
    var $last_insert_id;
    var $query;
    
    // Constructor function.
    function Database($error_mode = 0, $p_host = NULL, $p_user = NULL, $p_pass = NULL, $p_db_name = NULL) {
      $this->error_mode = $error_mode;
      if(isset($p_host)) { $this->host = $p_host; }
      if(isset($p_user)) { $this->username = $p_user; }
      if(isset($p_pass)) { $this->password = $p_pass; }
      if(isset($p_db_name)) { $this->db_name = $p_db_name; }
      set_error_handler(array($this, 'handle_error'));
    }
    
    // Connect to database.
    function Connect() {
      $this->dbc = mysql_connect($this->host, $this->username, $this->password);
      if(!$this->dbc) {
        trigger_error('Unable to connect to database.', E_USER_ERROR);
      }
      mysql_select_db($this->db_name) or trigger_error(mysql_error(), E_USER_ERROR);
      return TRUE;
    }
    
    // Disconnect from database.
    function Disconnect() {
      if($this->dbc) {
        mysql_close($this->dbc);
        return TRUE;
      }
    }
    
    // Perform a select query and return the records.
    function Select($p_fields = "*", $p_where = NULL, $p_order = NULL, $p_sort = 'ASC', $p_limit = NULL) {
      if($this->dbc) {
        $this->query = "SELECT $p_fields FROM " . $this->table;
        if(isset($p_where)) { $this->query .= " WHERE $p_where"; }
        if(isset($p_order)) { $this->query .= " ORDER BY $p_order $p_sort"; }
        if(isset($p_limit)) { $this->query .= " LIMIT $p_limit"; }
        $this->result_set = mysql_query($this->query) or trigger_error('Error in SELECT query: "' . $this->query . '"', E_USER_ERROR);
        if($this->result_set) {
          $this->record_count = mysql_num_rows($this->result_set);
          return mysql_fetch_array($this->result_set, MYSQL_ASSOC);
        } else {
          $this->record_count = 0;
        }
      } else {
        trigger_error('Error in SELECT procedure; not connected to database!', E_USER_ERROR);
      }
    }
    
    // Performs a raw query.
    function Query() {
      if($this->dbc) {
        $this->result_set = mysql_query($this->query) or trigger_error('Error in QUERY: "' . $this->query . '"', E_USER_ERROR);
        if($this->result_set) {
          $this->record_count = mysql_num_rows($this->result_set);
        } else {
          $this->record_count = 0;
        }
      } else {
        trigger_error('Error in SELECT procedure; not connected to database!', E_USER_ERROR);
      }
    }
    
    // Performs an insert query.
    function Insert($p_values) {
      if($this->dbc) {
        if(is_array($p_values)) {
          $this->query = "INSERT INTO " . $this->table . " (";
          
          foreach($p_values as $name=>$value) {
            $names .= "$name,";
            $values .= "'" . $this->escape_data($value, $this->dbc) . "',";
          }
          if(substr($names, -1) == ',') { $names = substr($names, 0, -1); }
          if(substr($values, -1) == ',') { $values = substr($values, 0, -1); }
          $this->query .= "$names) VALUES ($values)";
          $ret = mysql_query($this->query) or trigger_error('Error in INSERT: "' . $this->query . '"', E_USER_ERROR);
          if($ret) {
            $this->last_insert_id = mysql_insert_id($this->dbc);
            return TRUE;
          } else {
            $this->last_insert_id = 0;
          }
        }
      } else {
        trigger_error('Error in INSERT procedure; not connected to database!', E_USER_ERROR);
      }
    }
    
    // Escapes data.
    function escape_data($param1, $param2) {
      if(ini_get('magic_quotes_gpc')) {
        $data = stripslashes($param1);
      } else {
        $data = $param1;
      }
      
      return mysql_real_escape_string($data, $param2);
    }
    
    // Clears the result set.
    function ClearResults() {
      if($this->result_set) {
        @mysql_free_result($this->result_set);
      }
    }
    
    // Custom error handler.
    function handle_error($type, $string, $file, $line, $vars) {
      switch($type) {
        case E_USER_ERROR:
          switch($this->error_mode) {
            default:
            case 0:
              echo "Error: $string in $file on line $line<br />";
              print_r($vars);
              exit;
            case 1:
              echo "There has been an error, sorry for the inconvenience!";
              exit;
          }
        case E_USER_WARNING:
          echo "<pre><strong>Error</strong> [$type] $string<br /></pre>\n";
          break;
        case E_USER_NOTICE:
          echo "<pre><strong>Warning</strong> [$type] $string<br /></pre>\n";
          break;
      }
    }
  
  }
?>

An example of how it is used:

<?php
  require_once('cls_database.php');
  $db = New Database(0, 'localhost', 'username', 'password', 'DigiRev');
  $db->table = 'admin';
  
  if($db->Connect()) {
    echo "Connected to database!<br />";
  
    // Insert a new record.
    $fields = array();
    $fields['username'] = 'Danny';
    $fields['password'] = md5('12345678abcdefg');
    
    if($db->Insert($fields)) {
      echo 'Insert successful! ID of last insert is: ' . $db->last_insert_id;
    } else {
      echo 'There was an error inserting...';
    }
    
    unset($fields);
    // -----------------------------------------------
    
    
    // Select something from the database
    // Argument 1: name of fields to select, or * for all fields
    // Argument 2: stuff used in WHERE, ie: id=1
    // Argument 3: field to ORDER BY, ie: name
    // Argument 4: how to sort, ie: ASC or DESC
    // Argument 5: number of records to return (LIMIT)
    $fields = $db->Select('*', "username='DigiRev'", NULL, NULL, '1');
    
    // Check results.
    if($db->result_set) {
      echo 'Found ' . $db->record_count . ' record(s).<br />';
      echo 'ID: ' . $fields['id'] . '<br />';
      echo 'Name: ' . $fields['username'] . '<br />';
      echo 'Password: ' . $fields['password'] . '<br />';
      echo 'Last login: ' . $fields['last_login'];
      unset($fields);
    } else {
      echo 'No results found.';
    }
    
    $db->Disconnect();
  }
?>

Fire away...