PDO::prepare
(PHP 5 >= 5.1.0, PHP 7, PHP 8, PHP 8,PECL pdo >= 0.1.0)
PDO::prepare —
Prepares a statement for execution and returns a statement object
Опис
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.
Зауваження:
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.
Зауваження:
The parser used for emulated prepared statements and for
rewriting named or question mark style parameters supports the non standard
backslash escapes for single- and double quotes. That means that terminating
quotes immediately preceeded by a backslash are not recognized as such, which
may result in wrong detection of parameters causing the prepared statement to
fail when it is executed. A work-around is to not use emulated prepares for
such SQL queries, and to avoid rewriting of parameters by using a parameter style
which is natively supported by the driver.
As of PHP 7.4.0, question marks can be escaped by doubling them. That means that
the ??
string will be translated to ?
when sending the query to the database.
Параметри
query
-
This must be a valid SQL statement template for the target database server.
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.
Значення, що повертаються
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).
Зауваження:
Emulated prepared statements does not communicate with the database server
so PDO::prepare() does not check the statement.
Приклади
Приклад #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, [PDO::ATTR_CURSOR => PDO::CURSOR_FWDONLY]);
$sth->execute(['calories' => 150, 'colour' => 'red']);
$red = $sth->fetchAll();
/* Array keys can be prefixed with colons ":" too (optional) */
$sth->execute([':calories' => 175, ':colour' => 'yellow']);
$yellow = $sth->fetchAll();
?>
Приклад #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([150, 'red']);
$red = $sth->fetchAll();
$sth->execute([175, 'yellow']);
$yellow = $sth->fetchAll();
?>
Приклад #3 SQL statement template with question mark escaped
<?php
/* note: this is only valid on PostgreSQL databases */
$sth = $dbh->prepare('SELECT * FROM issues WHERE tag::jsonb ?? ?');
$sth->execute(['feature']);
$featureIssues = $sth->fetchAll();
$sth->execute(['performance']);
$performanceIssues = $sth->fetchAll();
?>