Binds a parameter to the specified variable name

# PDOStatement::bindParam

(PHP 5 >= 5.1.0, PHP 7, PHP 8, PECL pdo >= 0.1.0)

PDOStatement::bindParam — Binds a parameter to the specified variable name

### Description

public PDOStatement::bindParam(
string|int `$param`,
mixed `&$var`,
int `$type` = `PDO::PARAM_STR`,
int `$maxLength` = 0,
mixed `$driverOptions` = `null`
): bool

Binds a PHP variable to a corresponding named or question mark placeholder in the SQL statement that was used 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 (but may nonetheless be cast according to `type`). 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.

### Parameters

`param`

  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.

`var`

  Name of the PHP variable to bind to the SQL statement parameter.

`type`

  Explicit data type for the parameter using the `PDO::PARAM_*` constants. To return an INOUT parameter from a stored procedure, use the bitwise OR operator to set the `PDO::PARAM_INPUT_OUTPUT` bits for the `type` parameter.

`maxLength`

  Length of the data type. To indicate that a parameter is an OUT parameter from a stored procedure, you must explicitly set the length. Meaningful only when `type` parameter is `PDO::PARAM_INPUT_OUTPUT`.

`driverOptions`

### Return Values

Returns `true` on success or `false` on failure.

### Errors/Exceptions

Emits an error with level `E_WARNING` if the attribute `PDO::ATTR_ERRMODE` is set to `PDO::ERRMODE_WARNING`.

Throws a PDOException if the attribute `PDO::ATTR_ERRMODE` is set to `PDO::ERRMODE_EXCEPTION`.

### Examples

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);
/* Names can be prefixed with colons ":" too (optional) */
$sth->bindParam(':colour', $colour, PDO::PARAM_STR);
$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);
$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";
?>`

### See Also

- PDO::prepare() - Prepares a statement for execution and returns a statement object
- PDOStatement::execute() - Executes a prepared statement
- PDOStatement::bindValue() - Binds a value to a parameter

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