What is the difference between bindParam and bindValue?

Question

What’s the difference between Pdostatement::bindParam() and Pdostatement::bindValue()?

Answer 1

Differences in the receipt of values:

In accordance with rray quoted:

In bindParam() the expected argument is a reference (variable or constant) and cannot be a primitive type like a string or loose number, function/method return. bindValue() can receive references and values as argument.

$stmt->bindParam(':v1', 10); // Inválido
$stmt->bindParam(':v1', getValor()); // Inválido

Differences in PDOStatement::execute()

With bindParam, unlike bindValue, the variable is linked with a reference and will only be evaluated at the time when Pdostatement::execute() is called.

BindParam:

$sex = 'male';
$s = $dbh->prepare('SELECT name FROM students WHERE sex = :sex');
$s->bindParam(':sex', $sex);
$sex = 'female';
$s->execute(); // Executado quando $sex = 'female'

With bindValue:

$sex = 'male';
$s = $dbh->prepare('SELECT name FROM students WHERE sex = :sex');
$s->bindValue(':sex', $sex);
$sex = 'female';
$s->execute(); // Executado quando $sex = 'male'

Source

Answer 2

In the bindParam() the expected argument is a reference(variable or constant) cannot be a primitive type like a string or loose number, function/method return. bindValue() can receive references and values as argument, basically this is it.

The code below returns the error:

Fatal error: Cannot pass Parameter 2 by Reference in

$stmt->bindParam(':v1', 10); //inválido
$stmt->bindParam(':v1', getValor()); //inválido

Answer 3

Look at this SELECT what use, at least here is a real and commonly used example, as requested:

The bindParam always use with variareis if using a value type 'username' in place of the variable will give error pq it does not accept value, and the bindValue is the reverse I use the same value 'nome do usuário' ,1235456. I understand so bindParam parameters by reference use variable, bindValue even direct values without use of variable. I may not be right at some points but I hope to help clear up a little.

$usuario ='fulano';
$senha = '123456';
$conn = new PDO('mysql:host=localhost;dbname=nome_banco','','');
$query = $conn->prepare("SELECT * FROM usuarios WHERE usuario = :user AND senha = :pass ");
$query->bindParam(':user', $usuario, PDO::PARAM_STR);
#Uso o bindParam quando uso variáveis conforme acima.

$query->bindValue(':pass', sha1($senha), PDO::PARAM_STR);
#E uso bindValue quando vou passar o valor diretamente na classe pdo como está aqui acima.

#o sha1 vai me retornar um valor, como também poderia usar ex: 12345
$query->bindValue(':pass', 12345, PDO::PARAM_STR); 
#ou assim.
$query->bindValue(':pass', 'senha', PDO::PARAM_STR);


$query->execute();
$dados = $query->fetch(PDO::FETCH_ASSOC); 

This example might make it clearer how to use, I hope you understand.