API Documentation

Zend/Db/Expr.php

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Zend Framework

LICENSE

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Category
Zend  
Copyright
Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)  
License
New BSD License  
Package
Zend_Db  
Subpackage
Expr  
Version
$Id: Expr.php 24594 2012-01-05 21:27:01Z matthew $  

\Zend_Db_Expr

Package: Zend\Db\Expr

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  
Copyright
Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)  
License
New BSD License  

Properties

Propertyprotectedstring  $_expression= ''

Storage for the SQL expression.

Details
Type
string

Methods

methodpublic__construct( string $expression ) : void

Instantiate an expression, which is just a string stored as an instance member variable.

Parameters
Name Type Description
$expression string

The string containing a SQL expression.

methodpublic__toString( ) : string

Returns
Type Description
string The string of the SQL expression stored in this object.
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