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khosb/includes/kohana/modules/database/classes/Kohana/Database/Expression.php

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2012-11-09 12:18:50 +00:00
<?php defined('SYSPATH') OR die('No direct script access.');
/**
* Database expressions can be used to add unescaped SQL fragments to a
* [Database_Query_Builder] object.
*
* For example, you can use an expression to generate a column alias:
*
* // SELECT CONCAT(first_name, last_name) AS full_name
* $query = DB::select(array(DB::expr('CONCAT(first_name, last_name)'), 'full_name')));
*
* More examples are available on the [Query Builder](database/query/builder#database-expressions) page
*
* @package Kohana/Database
* @category Base
* @author Kohana Team
* @copyright (c) 2009 Kohana Team
* @license http://kohanaphp.com/license
*/
class Kohana_Database_Expression {
// Unquoted parameters
protected $_parameters;
// Raw expression string
protected $_value;
/**
* Sets the expression string.
*
* $expression = new Database_Expression('COUNT(users.id)');
*
* @param string $value raw SQL expression string
* @param array $parameters unquoted parameter values
* @return void
*/
public function __construct($value, $parameters = array())
{
// Set the expression string
$this->_value = $value;
$this->_parameters = $parameters;
}
/**
* Bind a variable to a parameter.
*
* @param string $param parameter key to replace
* @param mixed $var variable to use
* @return $this
*/
public function bind($param, & $var)
{
$this->_parameters[$param] =& $var;
return $this;
}
/**
* Set the value of a parameter.
*
* @param string $param parameter key to replace
* @param mixed $value value to use
* @return $this
*/
public function param($param, $value)
{
$this->_parameters[$param] = $value;
return $this;
}
/**
* Add multiple parameter values.
*
* @param array $params list of parameter values
* @return $this
*/
public function parameters(array $params)
{
$this->_parameters = $params + $this->_parameters;
return $this;
}
/**
* Get the expression value as a string.
*
* $sql = $expression->value();
*
* @return string
*/
public function value()
{
return (string) $this->_value;
}
/**
* Return the value of the expression as a string.
*
* echo $expression;
*
* @return string
* @uses Database_Expression::value
*/
public function __toString()
{
return $this->value();
}
/**
* Compile the SQL expression and return it. Replaces any parameters with
* their given values.
*
* @param mixed Database instance or name of instance
* @return string
*/
public function compile($db = NULL)
{
if ( ! is_object($db))
{
// Get the database instance
$db = Database::instance($db);
}
$value = $this->value();
if ( ! empty($this->_parameters))
{
// Quote all of the parameter values
$params = array_map(array($db, 'quote'), $this->_parameters);
// Replace the values in the expression
$value = strtr($value, $params);
}
return $value;
}
} // End Database_Expression