Method of subtracting two values from the sum of records coming from the Mysql database

Question

Good afternoon everyone, I’m creating a class that will work as a box

where it will sum all the records found in the bank with the column in the value of INPUT and OUTPUT and at the end I subtract Input - Output but it’s not working someone can tell me where I might be missing?

Function of class Lancamento

public function getSaldo(){

    $conexao = new Conexao();

    $sql1 = "SELECT SUM(valor) FROM $this->table WHERE tipo = Entrada";
    $sql2 = "SELECT SUM(valor) FROM $this->table WHERE tipo = Saida";

    $entrada = $conexao->login($sql1);

    $saida = $conexao->login($sql2);

    $saldo = $entrada[0] - $saida[0];

    return $saldo;


}

Login function

public function login($rawQuery, $params = array()):array
{

    $stmt = $this->query($rawQuery, $params);

    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

Page of function tests

<?php

require_once "../Controllers/Config.php";

$lancamento = new Lancamento;

$lancamento->getSaldo();


?>

The login class I am using temporarily I intend to implement a specific function for this case, I appreciate any help