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Last updated: Sat, 27 Jan 2007

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# PDO->prepare()

(no version information, might be only in CVS)

PDO->prepare() -- Prepares a statement for execution and returns a statement object

## Описание

class PDO {
PDOStatement prepare ( string statement [, array driver_options] )
}

Prepares an SQL statement to be executed by the PDOStatement->execute() method. The SQL statement can contain zero or more named (:name) or question mark (?) parameter markers for which real values will be substituted when the statement is executed. You cannot use both named and question mark parameter markers within the same SQL statement; pick one or the other parameter style.

You must include a unique parameter marker for each value you wish to pass in to the statement when you call PDOStatement->execute(). You cannot use a named parameter marker of the same name twice in a prepared statement. You cannot bind multiple values to a single named parameter in, for example, the IN() clause of an SQL statement.

Calling PDO->prepare() and PDOStatement->execute() for statements that will be issued multiple times with different parameter values optimizes the performance of your application by allowing the driver to negotiate client and/or server side caching of the query plan and meta information, and helps to prevent SQL injection attacks by eliminating the need to manually quote the parameters.

PDO will emulate prepared statements/bound parameters for drivers that do not natively support them, and can also rewrite named or question mark style parameter markers to something more appropriate, if the driver supports one style but not the other.

## Список параметров

`statement`

  This must be a valid SQL statement for the target database server.

`driver_options`

  This array holds one or more key=>value pairs to set attribute values for the PDOStatement object that this method returns. You would most commonly use this to set the `PDO::ATTR_CURSOR` value to `PDO::CURSOR_SCROLL` to request a scrollable cursor. Some drivers have driver specific options that may be set at prepare-time.

## Возвращаемые значения

If the database server successfully prepares the statement, PDO->prepare() returns a PDOStatement object. If the database server cannot successfully prepare the statement, PDO->prepare() returns `FALSE`.

## Примеры

Пример 1. Prepare an SQL statement with named parameters

`<?php
/* Execute a prepared statement by passing an array of values */
$sql = 'SELECT name, colour, calories
FROM fruit
WHERE calories < :calories AND colour = :colour';
$sth = $dbh->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_FWDONLY));
$sth->execute(array(':calories' => 150, ':colour' => 'red'));
$red = $sth->fetchAll();
$sth->execute(array('calories' => 175, 'colour' => 'yellow'));
$yellow = $sth->fetchAll();
?>`

Пример 2. Prepare an SQL statement with question mark parameters

`<?php
/* Execute a prepared statement by passing an array of values */
$sth = $dbh->prepare('SELECT name, colour, calories
FROM fruit
WHERE calories < ? AND colour = ?');
$sth->execute(array(150, 'red'));
$red = $sth->fetchAll();
$sth->execute(array(175, 'yellow'));
$yellow = $sth->fetchAll();
?>`

## Смотрите также

PDO->exec()
PDO->query()
PDOStatement->execute()

add a note User Contributed Notes
PDO->prepare()
jacques at chester dot id dot au
13-Nov-2006 06:07
`Watch out: prepared statements on MySQL barf if you try to pass in substitution tables for sql keywords, table names, view names and field names.
For example, this will not work:
$stmt = $dbh->prepare("SELECT :sqlAggregate( :fieldName) from :viewName";
You will get a MySQL error 1064 and a very unhelpful error message.
In short, you need to do string substitutions into your queries if you want configurable table names, aggregate keywords etc etc.
Which doesn't help at all in the "protection from injection attacks" thing. A very annoying discovery.`
william dot clarke at gmail dot com
31-Aug-2006 03:58
`Surely if you want to use prepared statements that way you should use the syntax in the second example:
eg.
instead of:
select id,name from demo_de where name LIKE :name OR name=:name
use:
select id,name from demo_de where name LIKE ? OR name=?
I believe you are supposed to either use distinct named parameters (name, name1) OR anonymous parameters (?s)`
roth at egotec dot com
30-Aug-2006 01:58
`Attention using MySQL and prepared statements.
Using a placeholder multiple times inside a statement doesn't work. PDO just translates the first occurance und leaves the second one as is.
select id,name from demo_de where name LIKE :name OR name=:name
You have to use
select id,name from demo_de where name LIKE :name OR name=:name2
and bind name two times. I don't know if other databases (for example Oracle or MSSQL) support multiple occurances. If that's the fact, then the PDO behaviour for MySQL should be changed.`
add a note
PDO->query() PDO->lastInsertId()

Last updated: Sat, 27 Jan 2007
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