Hyperlinks in php

ckflip

I am currently doing a project a uni and cant get my hyperlinks relating to my sql database to pull info from one page to another. I am very fustrated with this and if anyone can see the problem i would be glad of a tip. The worst thing is that the example was done by the lecturer. ive changed the user and password

I cant figue out how the student no is passed accross..

<?php

/
This is an example showing how to list records as hyperlink and associated key data/variables.
/

// Connect to server
// Replace username and password by your details

$db = @mysql_connect("localhost","user","password");
if (!$db)
{
do_error("Could not connect to the server");
}

// Connect to the database
// Note that your database will be called username

@mysql_select_db("students",$db)or do_error("Could not connect to the database");

// Run the search query

$result = mysql_query("SELECT * FROM students ORDER BY student_no",$db);

// Check that something was found

$rows=@mysql_num_rows($result);

// Output the search results

if(!$rows)
{
do_error("No results found");
}
else
{
echo "<table border=3 cellspacing=1 cellpadding=1
align=center bgcolor=lightgreen>\n";
echo "<caption><h2><font color=blue>Students</font></h2></caption>\n";
echo "<tr><th>Student No</th><th>Name</th></tr>\n";
while ($myrow = mysql_fetch_array($result))
{
printf("<tr><td>%s %s</td>\n",
$myrow["firstname"],$myrow["secondname"]);

            printf("<td><a href=\"mysql_Ex2_7b.php?studentid=%s\">%s</a></td></tr>\n",
            $myrow["student_no"],$myrow["student_no"]);
            }
     echo "</table>\n";

}

echo "<br><center>Click on the student number to update the entry</center><br>\n";
// Close the connection - not really necessary

mysql_close($db) or do_error("Could not close connection");

function do_error($error)
{
echo $error;
die;
}

PAGE 2 is.......

</html>

<html>
<head><title>Modify Student Form</title></head>

<body>
<h2 align=center><font color=blue>Modify a Student Record</font> </h2><p>

Enter the student details below:<br>

<?php

// Connect to server
// Replace username and password by your details

$db = @mysql_connect("localhost","user","pass");
if (!$db)
{
do_error("Could not connect to the server");
}

// Connect to the database
// Note that your database will be called username

@mysql_select_db("students",$db)or do_error("Could not connect to the database");

$result = mysql_query("SELECT * FROM students WHERE student_no=$studentid",$db);

// Check that something was found

$rows=@mysql_num_rows($result);

// Output the search results

if(!$rows)
{
do_error("No results found");
}
else
{
// Fetch the selected record from the database

    $myrow = mysql_fetch_array($result);

    echo "<pre>\n";
    printf("Student Number: %s<br>", $studentid);

    printf("<input type=\"hidden\" name=\"student_no\" value=\"%s\" size=5><br>",$myrow["student_no"]);
    printf("First Name:     <input type=\"text\" name=\"firstname\" value=\"%s\" size=20><br>",$myrow["firstname"]);
    printf("Second Name:    <input type=\"text\" name=\"secondname\" value=\"%s\" size=20><p>",$myrow["secondname"]);
    echo "</pre>";

}
mysql_close($db) or do_error("Could not close connection");

function do_error($error)
{
echo $error;
die;
}

?>
<input type="submit" value="Modify">
<input type="reset" value="Reset">
</form>

Frederick

what are these for %s

siwis

the %s are old style deprecated variable markers. A lot of the early tutorials use the %s method but its tremendously messy and extremely easy to get things wriong!

Anyway, to look at your problem.....

Firstly, to test whether the value of $studentid is actually being passed, simply echo it to screen at the top of your 2nd (ie the action file) page.

echo $studentid;

If you get nothing displayed then its possible you need to reference that variable in a different way.
Old tutorials always seem to assume that the php setting (global) for "Register_Globals" is set to ON.

What does "Register_Globals" do? Well it automatically maps variables to friendly names regardless of their method, ie if you POST a form each of its fieldnames become variables with the content of the field being its corresponding value. Thus a field named "USERNAME" is automatically mapped to a variable $USERNAME as soon as the form is submitted. If you GET a piece of information by passing it as part of the URL it once again gets mapped to a corresponsing friendly variable name ie for a page call to /page.php?USERNAME=username then a variable $USERNAME is created with a value of username.

When Register_Globals is off, this auto mapping does not occur and you then have to access those variables (they do still exist) in a different way.

Variables passed via POST should be referenced by;
$_POST['fieldname'];
OR
$HTTP_POST_VARS['fieldname'];

Variables passed via GET should be referenced by;
$_GET['fieldname'];
OR
$HTTP_GET_VARS['fieldname'];

Thus, to make your tutorial work, try changing the line (within PAGE 2)

$result = mysql_query("SELECT * FROM students WHERE student_no=$studentid",$db);

$result = mysql_query("SELECT * FROM students WHERE student_no=" . $HTTP_POST_VARS['studentid'] . "",$db);

siwis

Following your PM...

I've reread your original post......

Try my last suggestion but using $HTTP_GET_VARS['studentid']