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<?php
/**
* Zend Framework
*
* LICENSE
*
* This source file is subject to the new BSD license that is bundled
* with this package in the file LICENSE.txt.
* It is also available through the world-wide-web at this URL:
* http://framework.zend.com/license/new-bsd
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to license@zend.com so we can send you a copy immediately.
*
* @category Zend
* @package Zend_Db
* @subpackage Expr
* @copyright Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @version $Id: Expr.php 20096 2010-01-06 02:05:09Z bkarwin $
*/
/**
* Class for SQL SELECT fragments.
*
* This class simply holds a string, so that fragments of SQL statements can be
* distinguished from identifiers and values that should be implicitly quoted
* when interpolated into SQL statements.
*
* For example, when specifying a primary key value when inserting into a new
* row, some RDBMS brands may require you to use an expression to generate the
* new value of a sequence. If this expression is treated as an identifier,
* it will be quoted and the expression will not be evaluated. Another example
* is that you can use Zend_Db_Expr in the Zend_Db_Select::order() method to
* order by an expression instead of simply a column name.
*
* The way this works is that in each context in which a column name can be
* specified to methods of Zend_Db classes, if the value is an instance of
* Zend_Db_Expr instead of a plain string, then the expression is not quoted.
* If it is a plain string, it is assumed to be a plain column name.
*
* @category Zend
* @package Zend_Db
* @subpackage Expr
* @copyright Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
*/
class Zend_Db_Expr
{
/**
* Storage for the SQL expression.
*
* @var string
*/
protected $_expression;
/**
* Instantiate an expression, which is just a string stored as
* an instance member variable.
*
* @param string $expression The string containing a SQL expression.
*/
public function __construct($expression)
{
$this->_expression = (string) $expression;
}
/**
* @return string The string of the SQL expression stored in this object.
*/
public function __toString()
{
return $this->_expression;
}
}
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