Programming Forums > Web Development and Design > PHP

k4pil · Feb 15th, 2006, 12:45 PM

Hi there.

I am creating a user account for my site. Each user has a username and password. I am trying to check whether the username or password entered already exists, if it does then an error is displayed else data is added to the database.

However, im not able to get the logic sorted.

This is the part of the code i can't suss...eerything else e.g. database conncection and query is working fine.

(Toggle Plain Text)

include '../connect.php';

$query = "SELECT * FROM staff";
$result = mysql_query($query); 
$num = mysql_numrows($result);
$i=0;
while ($i < $num)
{
$usernameD=mysql_result($result,$i,"username");
$passwordD=mysql_result($result,$i,"password");

if ($usernameD == $Uusername || $Upassword == $password)
{
	echo "Details already exists. Please choose a different details";
	$value = "1";
	$i=$num;
}

$i++;
}


else
{
$query = "INSERT INTO staff VALUES ('$department', '$access' , '$Uusername' , '$Upassword' , '$name' , '$surname')";
$result = mysql_query($query); 

echo "<p>Data has been entered!!!";
}

I know its the else/while/if combo which isnt spot on, but im stuck.

Any help?

xavier · Feb 15th, 2006, 1:26 PM

You have :

(Toggle Plain Text)

while {
     if{
    }//end of if
}//end of while
else{}

else should be after if.
Another way you could do what you want is to

SELECT COUNT(*) FROM staff
WHERE staff.username == '$Uusername'

Then , if the query returns a number larger than 0, it means the user allready exists.

The sql might have mistakes , but you get the point. There's no reason to check if the password exists since you don't want 2 identical usernames in the first place

The Dark · Feb 15th, 2006, 6:12 PM

You don't want to put the else after the if in the loop, otherwise you will only be checking the first username!

As xavier said, limiting your SQL is a good idea, if you still want to go with the loop, use the value of $value as a test to see if the user name/password was found. You need to set $value to something other than 1 before the loop and the instead of "else" you could say

(Toggle Plain Text)

  if ($value != "1")

I would probaly call it something other than $value, maybe $userExists.

Also checking for username OR password seems odd - you have just created an easy way for someone to see if a particular password is in use by anyone!

Feb 15th, 2006, 12:45 PM	#1
k4pil Programmer Join Date: Aug 2005 Location: Leeds - UK Posts: 69 Rep Power: 4	Logic error Hi there. I am creating a user account for my site. Each user has a username and password. I am trying to check whether the username or password entered already exists, if it does then an error is displayed else data is added to the database. However, im not able to get the logic sorted. This is the part of the code i can't suss...eerything else e.g. database conncection and query is working fine. (Toggle Plain Text) include '../connect.php'; $query = "SELECT * FROM staff"; $result = mysql_query($query); $num = mysql_numrows($result); $i=0; while ($i < $num) { $usernameD=mysql_result($result,$i,"username"); $passwordD=mysql_result($result,$i,"password"); if ($usernameD == $Uusername \|\| $Upassword == $password) { echo "Details already exists. Please choose a different details"; $value = "1"; $i=$num; } $i++; } else { $query = "INSERT INTO staff VALUES ('$department', '$access' , '$Uusername' , '$Upassword' , '$name' , '$surname')"; $result = mysql_query($query); echo "<p>Data has been entered!!!"; } include '../connect.php'; $query = "SELECT * FROM staff"; $result = mysql_query($query); $num = mysql_numrows($result); $i=0; while ($i < $num) { $usernameD=mysql_result($result,$i,"username"); $passwordD=mysql_result($result,$i,"password"); if ($usernameD == $Uusername \|\| $Upassword == $password) { echo "Details already exists. Please choose a different details"; $value = "1"; $i=$num; } $i++; } else { $query = "INSERT INTO staff VALUES ('$department', '$access' , '$Uusername' , '$Upassword' , '$name' , '$surname')"; $result = mysql_query($query); echo "<p>Data has been entered!!!"; } I know its the else/while/if combo which isnt spot on, but im stuck. Any help?

Feb 15th, 2006, 1:26 PM	#2
xavier Professional Programmer Join Date: Oct 2004 Location: .ro Posts: 383 Rep Power: 4	You have : (Toggle Plain Text) while { if{ }//end of if }//end of while else{} while { if{ }//end of if }//end of while else{} else should be after if. Another way you could do what you want is to SELECT COUNT(*) FROM staff WHERE staff.username == '$Uusername' Then , if the query returns a number larger than 0, it means the user allready exists. The sql might have mistakes , but you get the point. There's no reason to check if the password exists since you don't want 2 identical usernames in the first place __________________ Don't take life too seriously, it's not permanent !

Feb 15th, 2006, 6:12 PM	#3
The Dark Expert Programmer Join Date: Jun 2005 Posts: 850 Rep Power: 4	You don't want to put the else after the if in the loop, otherwise you will only be checking the first username! As xavier said, limiting your SQL is a good idea, if you still want to go with the loop, use the value of $value as a test to see if the user name/password was found. You need to set $value to something other than 1 before the loop and the instead of "else" you could say (Toggle Plain Text) if ($value != "1") if ($value != "1") I would probaly call it something other than $value, maybe $userExists. Also checking for username OR password seems odd - you have just created an easy way for someone to see if a particular password is in use by anyone!

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Programming Forums > Web Development and Design > PHP

Logic error