PDO database abstraction layer that you can use in your applications to allow for future flexibility in your database choice and protect you from SQL Injection.

PDO_Database.php

<?php

// Define configuration
// May Include this in database configuration file
define("DB_HOST", "localhost");
define("DB_USER", "username");
define("DB_PASS", "password");
define("DB_NAME", "database");

/*
 PDO Database Class
 */
class PDO_Database {
    private $host = DB_HOST;
    private $user = DB_USER;
    private $pass = DB_PASS;
    private $dbname = DB_NAME;
    
    private $dbh;
    private $error;
    private $stmt;
    
    // Constructor
    public function __construct(){
        // Set DSN
        $dsn = 'mysql:host=' . $this->host . ';dbname=' . $this->dbname;
        
        // Set options
        $options = array(
            PDO::ATTR_PERSISTENT => true, 
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
        );
        
        // Create a new PDO instanace
        try{
            $this->dbh = new PDO($dsn, $this->user, $this->pass, $options);
        }
        // Catch any errors
        catch(PDOException $e){
            $this->error = $e->getMessage();
        }
    }
    
    // Prepare
    public function query($query){
        $this->stmt = $this->dbh->prepare($query);
    }
    
    // Bind
    public function bind($param, $value, $type = null){
        if (is_null($type)) {
          switch (true) {
            case is_int($value):
              $type = PDO::PARAM_INT;
              break;
            case is_bool($value):
              $type = PDO::PARAM_BOOL;
              break;
            case is_null($value):
              $type = PDO::PARAM_NULL;
              break;
            default:
              $type = PDO::PARAM_STR;
          }
        }
        $this->stmt->bindValue($param, $value, $type);
    }
    
    // Execute
    public function execute(){
        return $this->stmt->execute();
    }
    
    // Result Set
    public function resultset(){
        $this->execute();
        return $this->stmt->fetchAll(PDO::FETCH_ASSOC);
    }
    
    // Single
    public function single(){
        $this->execute();
        return $this->stmt->fetch(PDO::FETCH_ASSOC);
    }
    
    // Row Count
    public function rowCount(){
        return $this->stmt->rowCount();
    }
    
    // Last Insert Id
    public function lastInsertId(){
        return $this->dbh->lastInsertId();
    }
    
    /* TRANSACTIONS */
    // To begin a transaction
    public function beginTransaction(){
        return $this->dbh->beginTransaction();
    }
    // To end a transaction and commit your changes
    public function endTransaction(){
        return $this->dbh->commit();
    }
    // To cancel a transaction and roll back your changes
    public function cancelTransaction(){
        return $this->dbh->rollBack();
    }
    
    
    // Debug Dump Parameters
    public function debugDumpParams(){
        return $this->stmt->debugDumpParams();
    }
  
}

/* Example: Using your PDO class */

// Instantiate database.
$database = new PDO_Database();

/* [To Insert a new record] */
$database->query('INSERT INTO mytable (FName, LName, Age, Gender) VALUES (:fname, :lname, :age, :gender)');
// bind data
$database->bind(':fname', 'John');
$database->bind(':lname', 'Smith');
$database->bind(':age', '24');
$database->bind(':gender', 'male');
// execute
$database->execute();
//fetch last insert id
echo $database->lastInsertId();


/* [To Select a single row] */
$database->query('SELECT FName, LName, Age, Gender FROM mytable WHERE FName = :fname');
$database->bind(':fname', 'Jenny');
$row = $database->single();


/* [To Select multiple rows] */
$database->query('SELECT FName, LName, Age, Gender FROM mytable WHERE LName = :lname');
$database->bind(':lname', 'Smith');
$rows = $database->resultset();

// display the number of records returned.
echo $database->rowCount();