System to identify the user owns the PHP + Mysql topic

Question

GOOD AFTERNOON. I’m doing a help forum on my website, and I came across a question. I tried to make sure that when the topic owner had the question answered, he himself could close the topic. However, I have a certain message when trying to display the message for it to click. I tried that:

    <?php
        $connect = mysql_connect('localhost','root','');
        $db = mysql_select_db('registro');
        $id = $_GET["id"];
    $sql = "SELECT `Autor` FROM topicos WHERE `ID` = '$id'";
    $limite = mysql_query("$sql");
    if ($sql = $login_cookie ) { // o $login_cookie é minha variavel que seleciona o nome de usuário, quando ele está ativo na conta
// então, tentei comparar o nome de usuário com o nome do autor do tópico
        echo "Fechar tópico";
    } else {
        echo "oi"; // mensagem só para certificar se funcionou
    }
    ?>

But I didn’t get any results.

I don’t want a complete code, I just want to know how I could do it, that is, how I could do it.

Well, through this edition, I have come to say that this system would help me in several other functions also in my forum. I forgot to inform also what is happening: By entering this code, the message appears regardless of who is logged in. I don’t know if an image should help, but I believe it shows better what I do: http://i.imgur.com/Xrexho6.png

Answer 1

In the if are two signs of = for comparison. You didn’t get the result of yours query, for that I used the mysql_fetch_array().

<?php
    $connect = mysql_connect('localhost','root','');
    $db = mysql_select_db('registro');
    $id = $_GET["id"];

    $sql = "SELECT Autor FROM topicos WHERE ID = $id";
    $limite = mysql_query($sql);
    $res = mysql_fetch_array($limite);

    if ($res['Autor'] == $login_cookie ) { 
        echo "Fechar tópico";
    } else {
        echo "oi";
    }
?>

Verification in it SELECT:

SELECT Autor FROM topicos WHERE ID = $id AND Autor = '$login_cookie';

You are checking above to see if the specific topic was created by the logged-in Author.

Then you do another check asking how many rows have been returned. In this case return 1 or 0.

So:

$limite = mysql_query($sql);
$numlinha = mysql_num_rows($limite);

if($limite == 1)
    echo "Criou";
else
    echo "Não criou";