Query string error: Undefined index: id

PHP
1

Hello experts,
I am using a query string code. I want to “get” variable of one page to another page.

Query1.php:


<?php
$konek = mysql_connect("localhost","root","") or die("Cannot connect to server");
mysql_select_db("test",$konek) or die("Cannot connect to the database");
$query = mysql_query("select * from persons where id='1'");
$row = mysql_fetch_array($query);
$q= $row['details'];
?>

<a href='query_1.php?id=" . $q . "'>aa</a>

query_1.php


<?php
//$ab=1;

//if(isset($_GET['id']))
$ab= $_GET['id'];
echo $ab;
?>

The above code does not run and give error:

Notice: Undefined index: id

I am not geting what i am missing.
So, can some help me out wid my mistake…

2

What’s the value of the ‘id’ variable in the URL if you ‘view source’ on the query1.php page, before you click the link to query_1.php?

3

Also you should not be using the mysql_* functions as they are deprecated.

More info http://www.php.net/manual/en/intro.mysql.php

4

In your example, it looks like you are trying to use the $q variable without “going back into” PHP.

5

Well…, the code works perfectly fine in Query1.php page. But if i would nt have pasted my link
i.e echo “<a href='edit_last_follow.php?id=” . $a . “'>aa</a>”;

inspite only :

echo “<a href='edit_last_follow.php?id=” . $a . “'></a>”;

so how will i get the $a on my next page which is query_1.php page:



<?php  

if(isset($_GET['id']))   
$ab= $_GET['id'];  
echo $ab;  
?>

I want to echo $a of Query1.php page on query_1.php page.
I tried with the code above. I am stuck what i am missing.

6

PHP will only process PHP inside of <?php … ?> (technically not entirely correct, but close enough for this discussion)

So once you have ?> the rest is interpreted as HTML untl it next sees <?php

i.e. you need to enlose $q inside of <?php … ?>

Or

If your latter examples are closer to what you’re doing, you need to be careful using quotes so the output isn’t broken, eg. if the variale is 14

<a href='edit_last_follow.php?id=14'>aa</a>
<a href='edit_last_follow.php?id=14'></a>

then as long as edit_last_follow.php is the file with the echo $_get you should see it OK

7

I have enclosed it in my Query1.php page:


<?php  
$konek = mysql_connect("localhost","root","") or die("Cannot connect to server");  
mysql_select_db("test",$konek) or die("Cannot connect to the database");  
$query = mysql_query("select * from persons where id='1'");  
$row = mysql_fetch_array($query);  
$q= $row['details'];  

echo "<a href='query_1.php?id=" . $q . "'>aa</a>"; 

?>

But i dont want to give any link just get the variable $q in next page query_1.php

8

If you try

<?php
$konek = mysql_connect("localhost","root","") or die("Cannot connect to server");
mysql_select_db("test",$konek) or die("Cannot connect to the database");
$query = mysql_query("select * from persons where id='1'");
$row = mysql_fetch_array($query);
$q= $row['details'];
var_dump($row);
echo "<br />";
var_dump($q);
//echo "<a href='query_1.php?id=" . $q . "'>aa</a>";
?>

what do you see?

9

I get all my row value as an output.
See, what i want is get th variable value on next page

10

So you don’t want a link that you have to press, you just want to go directly to the query_1.php page without clicking anything?

If so, you could use:


header("Location: query_1.php?id=" . $q );

instead of echoing the link, I think. There’s probably a better way. When you displayed the link, did $q have the correct value in it? Remember we don’t know your database layout so can’t say whether $q= $row[‘details’] is going to need escaping for example.