Db/Expr.php
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- Category
- Zend
- Copyright
- Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
- License
- New BSD License
- Package
- Zend_Db
- Subpackage
- Expr
- Version
- $Id$
\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) 2005-2014 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.
Parameters
| Name | Type | Description |
|---|---|---|
| $expression | string | The string containing a SQL expression. |
__toString() : stringReturns
| Type | Description |
|---|---|
| string | The string of the SQL expression stored in this object. |