PDO::prepare
(PHP 5 >= 5.1.0, PHP 7, PECL pdo >= 0.1.0)
PDO::prepare — Prepares a statement for execution and returns a statement object
Description
Prepares an SQL statement to be executed by the PDOStatement::execute() method. The statement template can contain zero or more named (:name) or question mark (?) parameter markers for which real values will be substituted when the statement is executed. Both named and question mark parameter markers cannot be used within the same statement template; only one or the other parameter style. Use these parameters to bind any user-input, do not include the user-input directly in the query.
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 more than once in a prepared statement, unless emulation mode is on.
Note:
Parameter markers can represent a complete data literal only. Neither part of literal, nor keyword, nor identifier, nor whatever arbitrary query part can be bound using parameters. For example, you cannot bind multiple values to a single parameter in 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. Also, calling PDO::prepare() and PDOStatement::execute() helps to prevent SQL injection attacks by eliminating the need to manually quote and escape 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.
Parameters
-
statement -
This must be a valid SQL statement template 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.
Return Values
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 or emits
PDOException (depending on error handling).
Note:
Emulated prepared statements does not communicate with the database server so PDO::prepare() does not check the statement.
Examples
Example #1 SQL statement template 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();
?>
Example #2 SQL statement template 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();
?>
See Also
- 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
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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