PHP - Differences Between Isset($_get['']) And !$_get['']

Hi, I'm new to php and am attempting to build a site where the navigation and content is built with query functions. 
My current tables in my database are Categories, Products, and Variation.  So a person chooses a category -> then a product -> then a product page shows variations for that product. The problem I am currently having is after when a person selects a section the previous section selected is reset.  So lets a person selects a category the product list is shown, but when a person selects a product, the category is no longer selected in the navigation.  Or if someone selects product and sees all the variations, if he selects a variation the product ID is reset.  I've tried to comb through the internet for some type of solution.  I came across concatenating URL encode, but am not sure if this is the correct solution.  I tried concatenating one of my urls
with Code: [Select]
"<a href=\"product_detail.php?cat=" . urlencode($sel_cat["id"]) . '&' . "product=" . urlencode($sel_product['id']) . '&' . "var=" . urlencode($var["id"]) . "\"
its a bit of a stab in the dark. 

My $_GET function is
Code: [Select]
function find_selected_product() {
global $sel_cat;
global $sel_product;
global $sel_var;
if (isset($_GET['cat'])) {
$sel_cat = get_cat_by_id($_GET['cat']);
} elseif (isset($_GET['product'])) {
$sel_cat = NULL;
$sel_product = get_product_by_id($_GET['product']);
} elseif (isset($_GET['product'])) {
$sel_product = get_product_by_id($_GET['product']);
$sel_var = get_default_var($sel_product['id']);
} elseif (isset($_GET['var'])) {
$sel_product = NULL; //test
$sel_var = get_variation_by_id($_GET['var']);
} else {
$sel_cat = NULL;
$sel_product = NULL;
$sel_var = NULL;

}
}
My navigation code is
Code: [Select]
function public_navigation($sel_cat, $public = true) {
$output = "<td class=\"c1\"><div class=\"sidenav\"><ul>";
$cat_set = get_all_cats($public);
while ($cat = mysql_fetch_array($cat_set)) {
$output .= "<li>";
if ($cat["id"] == $sel_cat['id']) { $output .= "<a class=\"current\""; }
$output .= "<a href=\"index.php?cat=" . urlencode($cat["id"]) . "\">{$cat["cat_name"]}</a></li>";

}
$output .= "</ul>";

return $output;
}
My product is divided into gender and is written like

Code: [Select]
function cat_content_ladies($sel_cat, $sel_product, $female = true)
{
$output = "<ul class=\"regions\">";
$cat_set = get_all_cats($female);
while ($cat = mysql_fetch_array($cat_set))
{ if ($cat["id"] == $sel_cat['id'])
{
$product_set = get_products_for_female($cat["id"], $female);
$output .= "<tr>";
while ($product = mysql_fetch_array($product_set))
{
if ($cat["id"] == $sel_cat['id'])
{
$output .= "<tr>";
$output .= "<div class=\"pre\"><a href=\"product_detail.php?product=" . urlencode($product["id"]) . "\"></li>";
$output .= "<img src=\"{$product["img_src"]}\" height=\"121\" width=\"121\">";
$output .= "<div>{$product["prod_name"]}</a></div>";
}
}
$output .= "</tr>";
}
}
return $output;
}
My variation table is set up in thumb nails and is written in this function
Code: [Select]
function show_thumb($sel_product, $sel_var, $public = true)
{
$output = "<ul class=\"subjects\">";
$product_set = get_all_products($public);
while ($product = mysql_fetch_array($product_set)) {
$output .= "<li";
if ($product["id"] == $sel_product['id']) { $output .= " class=\"selected\""; }
//$output .= "><a href=\"product_detail.php?product=" . urlencode($product["id"]) .
//"\">{$product["id"]}</a></li>";
if ($product["id"] == $sel_product['id']) {
$var_set = get_variations_for_product($product["id"], $public);
$output .= "<ul class=\"pages\">";
while ($var = mysql_fetch_array($var_set)) {
$output .= "<li";
if ($var["id"] == $sel_var['id']) { $output .= " class=\"selected\""; }
$output .= "><a href=\"product_detail.php?var=" . urlencode($var["id"]) .
"\">{$var["id"]}</a></li>";

}
$output .= "</ul>";
}
}
$output .= "</ul>";
return $output;
}

 


any light on this subject would be greatly appreciated.

I am having problems with my $_GET.

When a user chooses an Article from "article_index.php", they click on a hyperlink, e.g.
Code: [Select]
<a href="<?php echo BASE_URL; ?>articles/postage-meters-can-save-you-money">
This triggers my Mod_Rewrite...
Code: [Select]
RewriteEngine on

#PRETTY: articles/postage-meters-can-save-you-money
#UGLY: article.php?slug=postage-meters-can-save-you-money

RewriteRule articles/([a-zA-Z0-9_-]+)$ article.php?slug=$1

Which should take them to "article.php?slug=postage-meters-can-save-you-money" and then this code is supposed to grab the "slug" and retrieve the Article...
Code: [Select]
// Attempt to Retrieve Article.
if (isset($_GET['slug'])){
// Slug found in URL.
// Set Slug.
$slug = $_GET['slug'];

That part is working fine, however, if I go into the Address Bar and delete out the slug, so my URL looks like this...
Code: [Select]
www.MySite.com/articles/">
I would expect the ELSE part of the above code to kick in...
Code: [Select]
}else{
// Slug not found in URL.
header("Location: " . BASE_URL . "index.php");
}//End of ATTEMPT TO RETRIEVE ARTICLE

Unfortunately I am just getting this error...
Quote

Not Found

The requested URL /articles/ was not found on this server.
Apache/2.0.59 (Unix) PHP/5.2.6 DAV/2 Server at local.debbie Port 80


Why is my ELSE not detecting that there is no slug??


Debbie

Hi

I have written a simple bit of code, i used to code php a little and have just decided to start coding php again but for the life of me can't work out why this isn't working, so if someone could help this would be great.

address

www.mysite.co.uk/index.php?vid=video2
<php
if (isset($_GET['vid'])){
   $video=$_GET['vid'];
}else{
$video="video1";
}

when i echo $video i only get video=1

I am trying to do isset($_GET but I have a bizarre problem come up.  I am using "id" as one of my fields but when I try to use it in the code it says it is not recognised.  However I use this field quite widely.

The code its coming up with is "Undefined variable: id" but I cant see why it has a problem with id.

My code is:

<?php

if(isset($_GET['id'])){

$sql = mysql_query("SELECT * FROM productfeed WHERE id='$id' LIMIT 1");

}
{


while($row = mysql_fetch_array($sql))

$id = $row['id'];
$image = $row['awImage'];
$link = $row['link'];
$description = $row['description'];
$fulldescription = $row['fulldescription'];
$price = $row['price'];

echo "<div class=\"productdisplayshell\"> <div class=\"productdisplayoutline\"> <div class=\"productborder\"><center>  <a href=\"$link\"  target=\"_blank\" ><img src=\"$image\" /></a> </center> </div></div> <div class=\"productdescriptionoutline\"><div class=\"productdescriptionbox\">  <a href=\"$link\"  target=\"_blank\" >$description</a> </div><div class=\"productfulldescriptionbox\">  $fulldescription </div></div> <div class=\"productpriceoutline\">  <div class=\"productpricebox\"><center>&#38;#163; $price</center></div>  <div class=\"productbuybutton\"><center><a href=\"$link\"  target=\"_blank\" ><img src=/images/buybutton.png /></a></center></div></div></div>";

} 


 

?>

soory guys .. actually i am trying to add pagination in script.. but its not pagging. but when i tried without isset($_get the code worked fine and then i tried to doing with isset($_get for a perticular cat but its not working. can someone see my code and tell me whats worng i have done.

<!DOCTYPE HTML>
<html>
    <head>
        
        
    </head>
<body>

<?php
// include database connection
include 'libs/db_connect.php';

// page is the current page, if there's nothing set, default is page 1
$page = isset($_GET['page']) ? $_GET['page'] : 1;

// set records or rows of data per page
$recordsPerPage = 1;

// calculate for the query LIMIT clause
$fromRecordNum = ($recordsPerPage * $page) - $recordsPerPage;

// select all data
$query = "SELECT
            *
        FROM
            posts
        ORDER BY
            post_id desc
        LIMIT
            {$fromRecordNum}, {$recordsPerPage}";
            
            /*
            page and its LIMIT clause looks like:
            1 = 0, 5
            2 = 5,10
            3 = 10,15
            4 = 15, 20
            5 = 20, 25
            */
        
$stmt = $con->prepare( $query );
$stmt->execute();

//this is how to get number of rows returned
$num = $stmt->rowCount();

//check if more than 0 record found
if($num>0){
    $cat=1;
    
    if(isset($_GET['cat'])){
                        $cat_id = $_GET['cat'];
                        $get_posts = "select * from posts where category_id = '$cat_id'";
                        $run_posts = mysql_query($get_posts);
                        while($row_posts = mysql_fetch_array($run_posts)){
                            $post_id = $row_posts['post_id'];
                            $post_title = $row_posts['post_title'];
                            $post_date = $row_posts['post_date'];
                            $post_author = $row_posts['post_author'];
                            $post_image = $row_posts['image'];
                            $post_content = substr($row_posts['post_content'],0,80);
                            
                            echo "
                            <div class='post_area'>
                            
                            <h4>
                                <a href = 'details.php?post=$post_id'>$post_title</a>
                            </h4>
                            <div class='date'><div id='com'> Date</div>$post_date</div><span style='font-size:12px'><i style='color:grey;font-size:10px'>Posted By</i> </b>$post_author</span>
                            
                            
                            <content><img src = '123dondadatest/news_images/$post_image' width = '100' height='100'/>
                            <div>$post_content <br/><a id='rmlink' href = 'details.php?post=$post_id'> Read More...</a></div><br /><br/><br/><br/>
                            
                            </div>
                            
                            ";
                            }
                    }

    
    // *************** <PAGING_SECTION> ***************
    echo "<div id='paging'>";

        // ***** for 'first' and 'previous' pages
        if($page>1){
            // ********** show the first page
            echo "<a href='" . $_SERVER['PHP_SELF'] . "' title='Go to the first page.' class='customBtn'>";
                echo "<span style='margin:0 .5em;'> << </span>";
            echo "</a>";
            
            // ********** show the previous page
            $prev_page = $page - 1;
            echo "<a href='" . $_SERVER['PHP_SELF'] . "?page={$prev_page}' title='Previous page is {$prev_page}.' class='customBtn'>";
                echo "<span style='margin:0 .5em;'> < </span>";
            echo "</a>";
            
        }
        
        
        // ********** show the number paging
        
        // find out total pages
        $query = "SELECT COUNT(*) as total_rows FROM posts";
        $stmt = $con->prepare( $query );
        $stmt->execute();

        $row = $stmt->fetch(PDO::FETCH_ASSOC);
        $total_rows = $row['total_rows'];
        
        $total_pages = ceil($total_rows / $recordsPerPage);

        // range of num links to show
        $range = 2;

        // display links to 'range of pages' around 'current page'
        $initial_num = $page - $range;
        $condition_limit_num = ($page + $range)  + 1;

        for ($x=$initial_num; $x<$condition_limit_num; $x++) {
            
            // be sure '$x is greater than 0' AND 'less than or equal to the $total_pages'
            if (($x > 0) && ($x <= $total_pages)) {
            
                // current page
                if ($x == $page) {
                    echo "<span class='customBtn' style='background:red;'>$x</span>";
                }
                
                // not current page
                else {
                    echo " <a href='{$_SERVER['PHP_SELF']}?page=$x' class='customBtn'>$x</a> ";
                }
            }
        }
        
        
        // ***** for 'next' and 'last' pages
        if($page<$total_pages){
            // ********** show the next page
            $next_page = $page + 1;
            echo "<a href='" . $_SERVER['PHP_SELF'] . "?page={$next_page}' title='Next page is {$next_page}.' class='customBtn'>";
                echo "<span style='margin:0 .5em;'> > </span>";
            echo "</a>";
            
            // ********** show the last page
            echo "<a href='" . $_SERVER['PHP_SELF'] . "?page={$total_pages}' title='Last page is {$total_pages}.' class='customBtn'>";
                echo "<span style='margin:0 .5em;'> >> </span>";
            echo "</a>";
        }
        
    echo "</div>";
    
    // ***** allow user to enter page number
    echo "<form action='" . $_SERVER['PHP_SELF'] . "' method='GET'>";
        echo "Go to page: ";
        echo "<input type='text' name='page' size='1' />";
        echo "<input type='submit' value='Go' class='customBtn' />";
    echo "</form>";    
    
    // *************** </PAGING_SECTION> ***************
}

// tell the user if no records were found
else{
    echo "<div class='noneFound'>No records found.</div>";
}
?>

</body>
</html>