用于更改密码的php

I do not understand why $colpassword does not return a value?: by application in Android step study the id , the old password and the new

$userId = $_POST["userId"];
$oldPassword = $_POST["oldPassword"];
$newPassword= $_POST["newPassword"];

$statement = mysqli_prepare($con, "SELECT password FROM users WHERE`E id = ?");
mysqli_stmt_bind_param($statement, 'i', $userId);

mysqli_stmt_execute($statement);

mysqli_stmt_store_result($statement);
mysqli_stmt_bind_result($statement, $colPassword);
mysqli_stmt_close($statement);
error_log($colPassword . "-" . $oldPassword, 3 , "/var/www/html/inf-5mgruppo1/messaggi.log");

$response = array();
$response["success"] = false;

if (password_verify($oldPassword, $colPassword)){
        $response["success"] = true;

        //update on database
        $hashedPassword = password_hash($newPassword, PASSWORD_DEFAULT);


        $statement_up = mysqli_prepare($con, "UPDATE users SET password = ? WHERE id = ?");
        mysqli_stmt_bind_param($statement_up, "si", $hashedPassword, $userId);
        mysqli_stmt_execute($statement_up);
        mysqli_stmt_close($statement_up);
}

echo json_encode($response);

You still have to fetch the data:

mysqli_stmt_bind_result($statement, $colPassword);
mysqli_stmt_fetch($statement); // fetch! 
mysqli_stmt_close($statement);