How define the variable type in PDOStatement::bindValue()?

Question

The PDOStatement::bindValue() method offers a way to specify the type of the variable bound:

PDOStatement::bindValue ( $parameter , $value [, $da

Answer 1

I'm no PDO-expert, but I can think of a few scenarioes where the data_type parameter is both useful and even needed.

Output parameters

When you define output or input/output parameters, you must provide both type and length of the expected output parameter.

Ref: http://www.php.net/manual/en/pdo.prepared-statements.php

Example #4

$stmt = $dbh->prepare("CALL sp_returns_string(?)");
$stmt->bindParam(1, $return_value, PDO::PARAM_STR, 4000); 

Example #5

$stmt = $dbh->prepare("CALL sp_takes_string_returns_string(?)");
$value = 'hello';
$stmt->bindParam(1, $value, PDO::PARAM_STR|PDO::PARAM_INPUT_OUTPUT, 4000); 

DBMs without implicit casting

Explained in another answer to this question...

When parameter is not bound to castable data

Even databases with casting abilities will not always be able to cast you variable correctly.

Ref: Reasons to strongly type parameters in PDO?

$limit = 1;

$dbh->prepare("SELECT * FROM items LIMIT :limit");
$dbh->bindParam(":limit", $limit, PDO::PARAM_STR); 
// Will throw "You have an error in your SQL syntax..."