Newbie w/ another mysql php question

Anon

Thanks to everyone who replied to my previous question, I hope you guys can help me out again. Like I said, my goal is to write a script to check to see if a user is in the databse already before they are added, so I thought of an idea where I would do a query to check if the user exists and if the number of rows returned was greater than 0 then the user already exists, but Im having a problem w/ this. Not only am I getting an error, but whenI load this page it crashes IE. Below is my code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<head>
<title>Test</title>
</head>
<body>
<?php
$db = mysql_connect("localhost", "root");
mysql_select_db("mydb",$db);
$NewUserID=1;
$NewUserBearID="Joe_Blow";
$NewUserSSN=999999999;
$Counter=1;
//$Result=mysql_query("select from User", $db);
$Record=mysql_query("select from User");
$NumOfRecords=mysql_num_rows($Record);

while ($Counter<=$NumOfRecords)
{

$Test=mysql_query("select * from User where ID=$Counter and BearID=$NewUserBearID");
$TestNum=mysql_num_rows($Test);
//echo $TestNum;
//if ($TestNum>0)
//{
//echo "We have a winner!";
//}

$Counter++;
}

</body>

anyone have any ideas? Thanks!

Laura Young

[deleted]

Your code is 'weird' to say the least :-)

The idea is there, but you are making some serious thinking-mistakes.

What are you trying to do?
- See if one particular person is in the database.

What do you know about that person?
- $NewUserBearID="Joe_Blow";

Is there a column in the table that contains users' newuserbearid info?
- Yes: BearID

So you want to know the info (*) from the table, where the bearid = $NewUserBearID...
- Yup, that's it.

then throw the select* from table; out, throw away the while loop, and just run

SELECT *
FROM table
WHERE BearID = $NewUserBearID;

and see if that gives any rows back (mysql_num_rows)

or, run this:

SELECT count(*) as cnt
FROM table
WHERE BearID = $NewUserBearID;

and fetch the first column of the first row. That will contain the number of times a record with BearID = $NewUserBearID was found.

Anon

If you are trying to check to see if a username is in the table, so you don't have two of the same usernames as I suspect, all you need to do is check the input when the user registers. If the database has this username you don't allow them to register until they pick a unique one. I use a function for this but you can do it many ways.

function getRow( $table, $fnm, $fval )
{
global $link;
$result = mysql_query( "SELECT * FROM $table WHERE $fnm='$fval'", $link );
if ( ! $result)
die ( "getRow fatal error: ".mysql_error() );
return mysql_fetch_array( $result );
}

Then just call the function and check the table, row, and value added. If the message doesn't print then you are o.k. and can move on.

if ( getRow( "login", "username", $form [username] ) )
$message .="Username \"$form[username]\" already exists.Try another<br>\n";
if ( $message == "" ) // we found no errors so do some more code
{
code her
}

trooper

Laura,

you have the right idea but are just making it slightly complicated

To check where a user already exists you need to have something that is totally unique to them. In today's world it is prefectly viable that two different people with the name "John Smith" would exist in a database.

One way people uniquely identify users is by their email addresses as usernames. After all no 2 people in the world will have the same email address.

It's easier to perform a check on an email address than a first/last name combination.

to do this you could do the following:

$result = mysql_query("select email from '<TABLE>' where email = '<EMAIL_ADDRESS>'");
$num_records = mysql_num_rows($result);

if($num_rows <1)
{
echo "this is a new user";
} else {

code if the email already exists
}

HTH