[SOLVED] error handling

[ngreenwood6]

I have a script where users can login to view certain pages of my site which works perfectly. I have also create a registration form for them to register with. If they leave the fields blank i have created the errors that it will give them. However, if they enter in an already used username it will add another user. I would like to know how to check the database to see if the user is there and if it is give an error. any help is appreciated.

[MadTechie]

Heres a very basic way.

 

$username will be the input

<?php
$username = "what ever";

$result = mysql_query("SELECT * from table WHERE username = '$username' ");
$num_rows = mysql_num_rows($result);
if($num_rows > 0)
{
die("User already exists");
}
?>

[ngreenwood6]

I am getting these errors when I try to do that:

 

Warning: mysqli_query() expects at least 2 parameters, 1 given in C:\wamp\www\login\register.php on line 21

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, null given in C:\wamp\www\login\register.php on line 22

 

Any help

[Adam]

Whats on lines 21 and 22? the code above?

 

 

[Adam]

Also if I were you i'd change the field in the database to unique.. that way mysql would give off an error if you try to enter duplicate usernames...

 

Adam

[MadTechie]

For MySQLi try

 

<?php
$link = mysqli_connect("localhost", "user", "password", "database");

if ($result = mysqli_query($link, "SELECT * from table WHERE username = '$username' "))
{

$num_rows = mysqli_num_rows($result);
mysqli_free_result($result);
if($num_rows > 0)
{
die("User already exists");
}
}
?>

 

OR

 

<?php
$mysqli = new mysqli("localhost", "user", "password", "database");

if ($result = $mysqli->query("SELECT * from table WHERE username = '$username' "))
{
/* determine number of rows result set */
$num_rows = $result->num_rows;
$result->close();
if($num_rows > 0)
{
die("User already exists");
}
}
?>

 

 

[ngreenwood6]

Thanks you madtechie your suggestion worked like a charm.