PHP If / else user exists on database set variable to 0 or 1

Question

I have this code to check if user exists in database. I want to assign $account to 1 if it exits, and 0 if it doesn't. I thought this code would work but its constantly setting $account to 0 so I think im missing a trick. Any help would be appreciated.

$con = mysql_connect(DB_HOST, DB_USER, DB_PASS) or die("Couldn't make connection.");

 if (!$con)
 {
 die('Could not connect: ' . mysql_error());
 }

mysql_select_db(DB_NAME, $con);

$sql="SELECT user_name FROM users";

$result = mysql_query($sql) or die(mysql_error());
$row = mysql_fetch_assoc($result);
if ($row['user_name'] == '$user_name'){
$account = 1;
}else{
        $account = 0;}

Thanks

when you compare strings it's better practice to use [strcomp](http://php.net/manual/en/function.strcmp.php) as follows: `if(strcomp($row['user_name'], $user_name) == 0)` — Nir Alfasi, Jul 06 '12 at 22:37
@alfasin: `===` would also be sufficient and more readable in this case ([related](http://stackoverflow.com/questions/3333353/php-string-comparison-vs-strcmp)). — jmdeldin, Jul 06 '12 at 22:43
@alfasin, best practise, really? I disagree, @jmdeldin says `===` is a much better choice since it's more readable. — John Carter, Jul 07 '12 at 01:12
@therefromhere and did you see what I replied ? now, if you quote me please try to be accurate: I said "better practice" not "best", `strcomp` preforms a binary safe string comparison which is more reliable than "==". Now, was I wrong ? — Nir Alfasi, Jul 07 '12 at 03:31

score 3 · Accepted Answer · answered Jul 06 '12 at 22:33

3

You can't put variables in a string if you use single quotes ' (plus it's not necessary!). Below rectifies that issue, and shortens your if/else statement into a one-liner.

$account = $row['user_name']==$user_name ? 1 : 0;

answered Jul 06 '12 at 22:33

MDEV

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You can put variables inside a string, however the wrapping quotations would have to be double in order for the variable to be interpolated. – trickyzter Jul 06 '12 at 22:37
Yes, that's why I stated ".. if you use single quotes" - but either quotes are pointless in this instance. – MDEV Jul 06 '12 at 22:38
1

You could also cast the result as an int: `(int) ($row['user_name'] == $user_name);` However, if you do rely on PHP's idea of equality with `==` or `if ($account)`, then explicitly converting a boolean to an int isn't needed (e.g., `true == '1'`). – jmdeldin Jul 07 '12 at 02:39

score 2 · Answer 2 · answered Jul 06 '12 at 22:40

I think this could be done a better way:

$con = mysql_connect(DB_HOST, DB_USER, DB_PASS) or die("Couldn't make connection.");

 if (!$con)
 {
 die('Could not connect: ' . mysql_error());
 }

mysql_select_db(DB_NAME, $con);

$account = (int)mysql_query("SELECT COUNT(*) FROM Users WHERE user_name='$user_name'");

That should store the correct value in account, i.e. 1 if the user is found and 0 if not.

score 1 · Answer 3 · answered Jul 06 '12 at 22:38

You're query is returning multiple rows, and you are doing the comparison with the first row. you need to do something like the follwing to specify a single user (see sql statement change):

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

$result = mysql_query($sql) or die(mysql_error());
$row = mysql_fetch_assoc($result);
if ($row['user_name'] == '$user_name'){
$account = 1;
}else{
        $account = 0;}

also, to iterate over rows, you can see this example from http://php.net/manual/en/function.mysql-fetch-assoc.php:

while ($row = mysql_fetch_assoc($result)) {
    echo $row["userid"];
    echo $row["fullname"];
    echo $row["userstatus"];
}

score 1 · Answer 4 · answered Jul 06 '12 at 22:43

Change:

if ($row['user_name'] == '$user_name'){

to:

if ($row['user_name'] == $user_name){

Single quotes signifies a string. So, by putting your variable between the single quotes, you're trying to match $row['user_name'] to $user_name (not string inside the $user_name variable - but STRING "$user_name").

Double quotes also signifies a string, but you can put your variable between double quotes and $row['user_name'] will match to $user_name (a string inside the variable).

So, the following two examples are correct, and yours isn't:

if ($row['user_name'] == $user_name){
if ($row['user_name'] == "$user_name"){

PHP If / else user exists on database set variable to 0 or 1

4 Answers4