Db/Expr.php
inherited
Classes
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 24593 2012-01-05 20:35:02Z matthew $
\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
Methods
__construct(string $expression) : voidInstantiate an expression, which is just a string stored as an instance member variable.
| Name | Type | Description |
|---|---|---|
| $expression | string | The string containing a SQL expression. |
__toString() : string| Type | Description |
|---|---|
| string | The string of the SQL expression stored in this object. |