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|
<?php
// Class providing generic data access functionality
class DatabaseHandler
{
// Hold an instance of the PDO class
private static $_mHandler;
// Private constructor to prevent direct creation of object
private function __construct()
{
}
// Return an initialized database handler
private static function GetHandler()
{
// Create a database connection only if one doesn't already exist
if (!isset(self::$_mHandler))
{
// Execute code catching potential exceptions
try
{
// Create a new PDO class instance
self::$_mHandler =
new PDO(PDO_DSN, DB_USERNAME, DB_PASSWORD,
array(PDO::ATTR_PERSISTENT => DB_PERSISTENCY));
// Configure PDO to throw exceptions
self::$_mHandler->setAttribute(PDO::ATTR_ERRMODE,
PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e)
{
// Close the database handler and trigger an error
self::Close();
trigger_error($e->getMessage(), E_USER_ERROR);
}
}
// Return the database handler
return self::$_mHandler;
}
// Clear the PDO class instance
public static function Close()
{
self::$_mHandler = null;
}
// Wrapper method for PDOStatement::execute()
public static function Execute($sqlQuery, $params = null)
{
// Try to execute an SQL query or a stored procedure
try
{
// Get the database handler
$database_handler = self::GetHandler();
// Prepare the query for execution
$statement_handler = $database_handler->prepare($sqlQuery);
// Execute query
$statement_handler->execute($params);
}
// Trigger an error if an exception was thrown when executing the SQL query
catch(PDOException $e)
{
// Close the database handler and trigger an error
self::Close();
trigger_error($e->getMessage(), E_USER_ERROR);
}
}
// Wrapper method for PDOStatement::fetchAll()
public static function GetAll($sqlQuery, $params = null,
$fetchStyle = PDO::FETCH_ASSOC)
{
// Initialize the return value to null
$result = null;
// Try to execute an SQL query or a stored procedure
try
{
// Get the database handler
$database_handler = self::GetHandler();
// Prepare the query for execution
$statement_handler = $database_handler->prepare($sqlQuery);
// Execute the query
$statement_handler->execute($params);
// Fetch result
$result = $statement_handler->fetchAll($fetchStyle);
}
// Trigger an error if an exception was thrown when executing the SQL query
catch(PDOException $e)
{
// Close the database handler and trigger an error
self::Close();
LINE 89:trigger_error($e->getMessage(), E_USER_ERROR);
}
// Return the query results
return $result;
}
// Wrapper method for PDOStatement::fetch()
public static function GetRow($sqlQuery, $params = null,
$fetchStyle = PDO::FETCH_ASSOC)
{
// Initialize the return value to null
$result = null;
// Try to execute an SQL query or a stored procedure
try
{
// Get the database handler
$database_handler = self::GetHandler();
// Prepare the query for execution
$statement_handler = $database_handler->prepare($sqlQuery);
// Execute the query
$statement_handler->execute($params);
// Fetch result
$result = $statement_handler->fetch($fetchStyle);
}
// Trigger an error if an exception was thrown when executing the SQL query
catch(PDOException $e)
{
// Close the database handler and trigger an error
self::Close();
line 89 --trigger_error($e->getMessage(), E_USER_ERROR);
}
// Return the query results
return $result;
}
// Return the first column value from a row
public static function GetOne($sqlQuery, $params = null)
{
// Initialize the return value to null
$result = null;
// Try to execute an SQL query or a stored procedure
try
{
// Get the database handler
$database_handler = self::GetHandler();
// Prepare the query for execution
$statement_handler = $database_handler->prepare($sqlQuery);
// Execute the query
$statement_handler->execute($params);
// Fetch result
$result = $statement_handler->fetch(PDO::FETCH_NUM);
/* Save the first value of the result set (first column of the first row)
to $result */
$result = $result[0];
}
// Trigger an error if an exception was thrown when executing the SQL query
catch(PDOException $e)
{
// Close the database handler and trigger an error
self::Close();
trigger_error($e->getMessage(), E_USER_ERROR);
}
// Return the query results
return $result;
}
}
?> |
