What’s wrong with this query?

Question

Okay, I’m trying to select a database through ajax using jQuery. Below are excerpts of the code I’m using and more explanations:

Ajax function

function carregaRegistros(dia, mes, ano) {

    dia = parseInt(dia);
    mes = parseInt(mes);
    ano = parseInt(ano);

    $.ajax({
        method: "POST",
        url: "PHP-Files/carregaRegistros.php",
        data: {dia: dia, mes: mes, ano: ano},
        success: function(result){
            alert(result);
        }
    });
}

Query

// Cria conexão
$conn = new mysqli($servername, $username, $password, $dbname);
// Verifica conexão
if ($conn->connect_error) {
    die("Erro de conexão: " . $conn->connect_error);
}

$dia = $_POST["dia"];
$mes = $_POST["mes"];
$ano = $_POST["ano"];

$sql = "SELECT Cliente, TotalDeHoras, HoraDeEntrada, HoraDeSaida FROM 
apontamentos WHERE Dia='$dia' AND Mes='$mes' AND Ano='$ano'";

if ($conn->query($sql) === TRUE) {
    echo "Apontamento incluído com sucesso!";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();

I already checked and the connection is being made and the data is being passed correctly, however I get an error message as return which indicates that the select is not being done. I don’t understand why this is happening, and I’m kind of new at this part of creating database connections. If I have omitted any important information please ask in the comments

Answer 1

A select query will not return a true one, as in this comparison you are trying to do. You can even check if it will not return errors, but this comparison that is doing it will never enter the if. That is why your error does not return any error, because there are no errors... Voce can try to do so:

if ($conn->query($sql)) {}

I believe I’ve overcome your doubt.

Answer 2

The correct is to check if there is any record

select Count checks the number of non-zero lines within the count what you want to do!

  $result = $conn->query("SELECT COUNT(*) FROM apontamentos WHERE Dia='$dia' AND Mes='$mes' AND Ano='$ano''");

  $row = $result->fetch_row();

  if ($row[0] > 0) {
      echo "Apontamento incluído com sucesso!";
  } else {
      echo "Error: " . $sql . "<br>" . $conn->error;
  }

or

$result = $conn->query("SUA QUERY")); 
if($result->num_rows){
   // echo "Apontamento incluído com sucesso!";
}else{
   // echo "Error: " . $sql . "<br>" . $conn->error;
}

To return the records

$result = $conn->query("SUA QUERY")); 
if($result->num_rows){

   while($row = $result->fetch_assoc()) {
        $Cliente = $row["Cliente"];
        $TotalDeHoras = $row["TotalDeHoras"];
        $HoraDeEntrada = $row["HoraDeEntrada"];
        $HoraDeSaida = $row["HoraDeSaida"];

     }

   // echo "Apontamento incluído com sucesso!";
}else{
   // echo "Error: " . $sql . "<br>" . $conn->error;
}