PHP Mysql query is returning null [closed]

Question

I have a simple PHP login function. Within this function, I am checking to see if the user exist by making a MySQL query that is selecting username from a table and counting the number of rows that is returned. I am having trouble with the query returning null when I know for a fact that the table contains the username.

Here is my code.

function login($user_name, $password) {
    $db1 = new DB_CONNECT();        
    $db1->connect();

    $query = "SELECT user_name FROM users WHERE user_name = '$user_name'";
    $result = $db1->makeAQuery($query);

    if (mysql_num_rows($result) == 1) {
        //check the password
    }
    else {
        //no user exist 
    }
}

I know that the username and password that are coming in are OK and I trim for any white spaces before I sent them to the function. I know that the database connection is working because it works on the rest of my PHP code. The only error that I am getting is one that mentions that the mysql_num_rows "expects parameter 1 to be resource, null given"

Database class

class DB_CONNECT {
    function connect() {
        // import database connection variables
        require_once __DIR__ . '/db_config.php';
        $con = mysql_connect(DB_SERVER, DB_USER, DB_PASSWORD) or die(mysql_error());

        // Selecing database
        mysql_select_db(DB_DATABASE, $con) or die(mysql_error());
    }
    function makeAQuery($query) {
        $result = mysql_query($query) or die(mysql_error());        
    } 
    function close() {
       // closing db connection
    mysql_close();
    }
}

as above, but also STOP using mysql_* built in functions. php.net/manual/en/function.mysql-num-rows.php — djjjuk
– djjjuk, Commented Mar 14, 2013 at 13:43
possible duplicate stackoverflow.com/questions/6603974/mysql-returning-empty-set — Sachin Prasad
– Sachin Prasad, Commented Mar 14, 2013 at 13:46
possible solution to all your problems: stackoverflow.com/questions/826981/… best practices — Kris
– Kris, Commented Mar 14, 2013 at 13:46

rinchik · Accepted Answer · 2013-03-14 14:06:57Z

2

This should work:

"SELECT user_name FROM users WHERE user_name = '".$user_name."'";

Also

change this:

function makeAQuery($query) {
    $result = mysql_query($query) or die(mysql_error());        
}

to

function makeAQuery($query) {
    $result = mysql_query($query) or die(mysql_error());      
    return   $result;
}

answered Mar 14, 2013 at 14:06

rinchik

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1 Comment

Bency76 Over a year ago

The Return statement did it. After all that, I forgot a simple statement.

George Mickleburgh · Accepted Answer · 2013-03-14 13:40:44Z

-1

Maybe try removing the spaces between the = in the query.

"SELECT user_name FROM users WHERE user_name='$user_name'"

Your script may be returning null because the query could not run.

answered Mar 14, 2013 at 13:40

George Mickleburgh

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3 Comments

echo_Me Over a year ago

i can make it WHERE user_name = many_space_here '$user_name' and it will work

George Mickleburgh Over a year ago

Ah sorry, I forgot MySQL does not care for whitespace.

Bency76 Over a year ago

With or without spaces, the samething

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