78 lines
2.5 KiB
PHP
78 lines
2.5 KiB
PHP
<?php
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/**
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* Zend Framework
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*
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* LICENSE
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*
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* This source file is subject to the new BSD license that is bundled
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* with this package in the file LICENSE.txt.
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* It is also available through the world-wide-web at this URL:
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* http://framework.zend.com/license/new-bsd
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* If you did not receive a copy of the license and are unable to
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* obtain it through the world-wide-web, please send an email
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* to license@zend.com so we can send you a copy immediately.
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*
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* @category Zend
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* @package Zend_Db
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* @subpackage Expr
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* @copyright Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
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* @license http://framework.zend.com/license/new-bsd New BSD License
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* @version $Id: Expr.php 9101 2008-03-30 19:54:38Z thomas $
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*/
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/**
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* Class for SQL SELECT fragments.
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*
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* This class simply holds a string, so that fragments of SQL statements can be
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* distinguished from identifiers and values that should be implicitly quoted
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* when interpolated into SQL statements.
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*
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* For example, when specifying a primary key value when inserting into a new
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* row, some RDBMS brands may require you to use an expression to generate the
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* new value of a sequence. If this expression is treated as an identifier,
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* it will be quoted and the expression will not be evaluated. Another example
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* is that you can use Zend_Db_Expr in the Zend_Db_Select::order() method to
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* order by an expression instead of simply a column name.
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*
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* The way this works is that in each context in which a column name can be
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* specified to methods of Zend_Db classes, if the value is an instance of
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* Zend_Db_Expr instead of a plain string, then the expression is not quoted.
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* If it is a plain string, it is assumed to be a plain column name.
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*
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* @category Zend
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* @package Zend_Db
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* @subpackage Expr
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* @copyright Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
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* @license http://framework.zend.com/license/new-bsd New BSD License
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*/
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class Zend_Db_Expr
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{
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/**
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* Storage for the SQL expression.
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*
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* @var string
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*/
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protected $_expression;
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/**
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* Instantiate an expression, which is just a string stored as
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* an instance member variable.
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*
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* @param string $expression The string containing a SQL expression.
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*/
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public function __construct($expression)
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{
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$this->_expression = (string) $expression;
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}
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/**
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* @return string The string of the SQL expression stored in this object.
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*/
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public function __toString()
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{
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return $this->_expression;
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}
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}
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