(PHP 5 >= 5.1.0, PECL pdo:0.1-1.0.3)
PDOStatement->bindParam() — Binds a parameter to the specified variable name
Binds a PHP variable to a corresponding named or question mark placeholder in the SQL statement that was use to prepare the statement. Unlike PDOStatement->bindValue(), the variable is bound as a reference and will only be evaluated at the time that PDOStatement->execute() is called.
Most parameters are input parameters, that is, parameters that are used in a read-only fashion to build up the query. Some drivers support the invocation of stored procedures that return data as output parameters, and some also as input/output parameters that both send in data and are updated to receive it.
Parameter identifier. For a prepared statement using named placeholders, this will be a parameter name of the form :name. For a prepared statement using question mark placeholders, this will be the 1-indexed position of the parameter.
Name of the PHP variable to bind to the SQL statement parameter.
Explicit data type for the parameter using the PDO::PARAM_* constants. Defaults to PHP native type. To return an INOUT parameter from a stored procedure, use the bitwise OR operator to set the PDO::PARAM_INPUT_OUTPUT bits for the data_type parameter.
Length of the data type. To indicate that a parameter is an OUT parameter from a stored procedure, you must explicitly set the length.
如果成功则返回 TRUE，失败则返回 FALSE。
Example#1 Execute a prepared statement with named placeholders
<?php
/* Execute a prepared statement by binding PHP variables */
$calories = 150;
$colour = 'red';
$sth = $dbh->prepare('SELECT name, colour, calories
FROM fruit
WHERE calories < :calories AND colour = :colour');
$sth->bindParam(':calories', $calories, PDO::PARAM_INT);
$sth->bindParam(':colour', $colour, PDO::PARAM_STR, 12);
$sth->execute();
?>
Example#2 Execute a prepared statement with question mark placeholders
<?php
/* Execute a prepared statement by binding PHP variables */
$calories = 150;
$colour = 'red';
$sth = $dbh->prepare('SELECT name, colour, calories
FROM fruit
WHERE calories < ? AND colour = ?');
$sth->bindParam(1, $calories, PDO::PARAM_INT);
$sth->bindParam(2, $colour, PDO::PARAM_STR, 12);
$sth->execute();
?>
Example#3 Call a stored procedure with an INOUT parameter
<?php
/* Call a stored procedure with an INOUT parameter */
$colour = 'red';
$sth = $dbh->prepare('CALL puree_fruit(?)');
$sth->bindParam(1, $colour, PDO::PARAM_STR|PDO::PARAM_INPUT_OUTPUT, 12);
$sth->execute();
print("After pureeing fruit, the colour is: $colour");
?>