PDO::prepare

(PHP 5 >= 5.1.0, PECL pdo >= 0.1.0)

PDO::prepare — Prepares a statement for execution and returns a statement object

Описание

PDOStatement PDO::prepare ( string $statement [, array $driver_options= array() ] )

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() emits PDOException.

Замечание: Emulated prepared statements does not communicate with the database server so PDO::prepare() does not check the statement.

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() - Execute an SQL statement and return the number of affected rows
PDO::query() - Executes an SQL statement, returning a result set as a PDOStatement object
PDOStatement::execute() - Executes a prepared statement