1 <?php

     2 /**

     3  * Zend Framework

     4  *

     5  * LICENSE

     6  *

     7  * This source file is subject to the new BSD license that is bundled

     8  * with this package in the file LICENSE.txt.

     9  * It is also available through the world-wide-web at this URL:

    10  * http://framework.zend.com/license/new-bsd

    11  * If you did not receive a copy of the license and are unable to

    12  * obtain it through the world-wide-web, please send an email

    13  * to license@zend.com so we can send you a copy immediately.

    14  *

    15  * @category   Zend

    16  * @package    Zend_Db

    17  * @subpackage Expr

    18  * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

    19  * @license    http://framework.zend.com/license/new-bsd     New BSD License

    20  * @version    $Id: Expr.php 20096 2010-01-06 02:05:09Z bkarwin $

    21  */

    22 

    23 

    24 /**

    25  * Class for SQL SELECT fragments.

    26  *

    27  * This class simply holds a string, so that fragments of SQL statements can be

    28  * distinguished from identifiers and values that should be implicitly quoted

    29  * when interpolated into SQL statements.

    30  *

    31  * For example, when specifying a primary key value when inserting into a new

    32  * row, some RDBMS brands may require you to use an expression to generate the

    33  * new value of a sequence.  If this expression is treated as an identifier,

    34  * it will be quoted and the expression will not be evaluated.  Another example

    35  * is that you can use Zend_Db_Expr in the Zend_Db_Select::order() method to

    36  * order by an expression instead of simply a column name.

    37  *

    38  * The way this works is that in each context in which a column name can be

    39  * specified to methods of Zend_Db classes, if the value is an instance of

    40  * Zend_Db_Expr instead of a plain string, then the expression is not quoted.

    41  * If it is a plain string, it is assumed to be a plain column name.

    42  *

    43  * @category   Zend

    44  * @package    Zend_Db

    45  * @subpackage Expr

    46  * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

    47  * @license    http://framework.zend.com/license/new-bsd     New BSD License

    48  */

    49 class Zend_Db_Expr

    50 {

    51     /**

    52      * Storage for the SQL expression.

    53      *

    54      * @var string

    55      */

    56     protected $_expression;

    57 

    58     /**

    59      * Instantiate an expression, which is just a string stored as

    60      * an instance member variable.

    61      *

    62      * @param string $expression The string containing a SQL expression.

    63      */

    64     public function __construct($expression)

    65     {

    66         $this->_expression = (string) $expression;

    67     }

    68 

    69     /**

    70      * @return string The string of the SQL expression stored in this object.

    71      */

    72     public function __toString()

    73     {

    74         return $this->_expression;

    75     }

    76 

    77 }