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PHP PDO Singleton Class
<?php
/**
* PDO SINGLETON CLASS
*
* @author Tony Landis
* @link http://www.tonylandis.com
* @license Use how you like it, just please don't remove or alter this PHPDoc
*/
class sdb
{
/**
* The singleton instance
*
*/
static private $PDOInstance;
/**
* Creates a PDO instance representing a connection to a database and makes the instance available as a singleton
*
* @param string $dsn The full DSN, eg: mysql:host=localhost;dbname=testdb
* @param string $username The user name for the DSN string. This parameter is optional for some PDO drivers.
* @param string $password The password for the DSN string. This parameter is optional for some PDO drivers.
* @param array $driver_options A key=>value array of driver-specific connection options
*
* @return PDO
*/
public function __construct($dsn, $username=false, $password=false, $driver_options=false)
{
if(!self::$PDOInstance) {
try {
self::$PDOInstance = new PDO($dsn, $username, $password, $driver_options);
} catch (PDOException $e) {
die("PDO CONNECTION ERROR: " . $e->getMessage() . "<br/>");
}
}
return self::$PDOInstance;
}
/**
* Initiates a transaction
*
* @return bool
*/
public function beginTransaction() {
return self::$PDOInstance->beginTransaction();
}
/**
* Commits a transaction
*
* @return bool
*/
public function commit() {
return self::$PDOInstance->commit();
}
/**
* Fetch the SQLSTATE associated with the last operation on the database handle
*
* @return string
*/
public function errorCode() {
return self::$PDOInstance->errorCode();
}
/**
* Fetch extended error information associated with the last operation on the database handle
*
* @return array
*/
public function errorInfo() {
return self::$PDOInstance->errorInfo();
}
/**
* Execute an SQL statement and return the number of affected rows
*
* @param string $statement
*/
public function exec($statement) {
return self::$PDOInstance->exec($statement);
}
/**
* Retrieve a database connection attribute
*
* @param int $attribute
* @return mixed
*/
public function getAttribute($attribute) {
return self::$PDOInstance->getAttribute($attribute);
}
/**
* Return an array of available PDO drivers
*
* @return array
*/
public function getAvailableDrivers(){
return Self::$PDOInstance->getAvailableDrivers();
}
/**
* Returns the ID of the last inserted row or sequence value
*
* @param string $name Name of the sequence object from which the ID should be returned.
* @return string
*/
public function lastInsertId($name) {
return self::$PDOInstance->lastInsertId($name);
}
/**
* Prepares a statement for execution and returns a statement object
*
* @param string $statement A valid SQL statement for the target database server
* @param array $driver_options Array of one or more key=>value pairs to set attribute values for the PDOStatement obj
returned
* @return PDOStatement
*/
public function prepare ($statement, $driver_options=false) {
if(!$driver_options) $driver_options=array();
return self::$PDOInstance->prepare($statement, $driver_options);
}
/**
* Executes an SQL statement, returning a result set as a PDOStatement object
*
* @param string $statement
* @return PDOStatement
*/
public function query($statement) {
return self::$PDOInstance->query($statement);
}
/**
* Execute query and return all rows in assoc array
*
* @param string $statement
* @return array
*/
public function queryFetchAllAssoc($statement) {
return self::$PDOInstance->query($statement)->fetchAll(PDO::FETCH_ASSOC);
}
/**
* Execute query and return one row in assoc array
*
* @param string $statement
* @return array
*/
public function queryFetchRowAssoc($statement) {
return self::$PDOInstance->query($statement)->fetch(PDO::FETCH_ASSOC);
}
/**
* Execute query and select one column only
*
* @param string $statement
* @return mixed
*/
public function queryFetchColAssoc($statement) {
return self::$PDOInstance->query($statement)->fetchColumn();
}
/**
* Quotes a string for use in a query
*
* @param string $input
* @param int $parameter_type
* @return string
*/
public function quote ($input, $parameter_type=0) {
return self::$PDOInstance->quote($input, $parameter_type);
}
/**
* Rolls back a transaction
*
* @return bool
*/
public function rollBack() {
return self::$PDOInstance->rollBack();
}
/**
* Set an attribute
*
* @param int $attribute
* @param mixed $value
* @return bool
*/
public function setAttribute($attribute, $value ) {
return self::$PDOInstance->setAttribute($attribute, $value);
}
}
?>
@mihail-minkov

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commented Jun 11, 2013

Your implementation saved me from a long and lasting headache. I was having problems passing session variables because of PDO and with this my script worked as it was supposed to. Thank you.

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