Creating a list divided into categories

Anon

Hi!

This is my second post on this subject...

With the following code I\'m trying to create a list of links divided into categories. First I try to get the first category and then I try to call each link that belongs to the category recursively. Here\'s the code:

$query = mysql_query(\"SELECT links.link_name, links.url, links.link_parent, categories.category_id, categories.category_name, categories.category_parent, portals.portal_id, portals.portal_parent FROM categories, portals, links WHERE portals.portal_parent=1 AND portals.portal_id=categories.category_parent AND categories.category_id=links.link_parent\");

if (!$query) {
echo(\"<P>Error retrieving links from database!<BR>\".
\"Error: \" . mysql_error());
exit();
}

while ($sql = mysql_fetch_array($query)) {
$cat_name = $sql[\"category_name\"];

echo(\"$cat_name: \");
linklist2();
}

Anyway...it doesn\'t work...Does anyone know what I\'m doing wrong (..please give examples of code that would work - if possible :-)

Best regards

Simon

Anon

Could you explain what exactly doesn't work? Are you getting a mysql error? no output? incomplete output? the wrong output?

One thing I see right off is a problem in your logic. What your program is saying is 'display the category name from the first record, then create links from all the remaining records'.

I think what you want is something like
//While you can fetch another row
{
//if the category name is different from the last one
{
//display category name
}
// create link
}

Of course for this to work, your SQL statement would have to order the records by category.

HTH,
Beth

Anon

Hi Beth,

I've got to categories in my database:

-Search (id=2)
-WWW (id=1)

I don't get any errors or anything the only thing get is this:

Search:

The first category is showed, but the links belonging to it isn't....The part of my code that shows the first category must be functioning...but the function 'linklist2' isn't..at least none of links belonging to Search is showed...'WWW' isn't showed either so I guess the 'while' sentence is working to it's fullest...?

I tried another peace of code that looked sometihng like this (that does what you tell me to do in your "code"):

But it didn't help...Do you have any idea of what I'm doing wrong?!

Best regards

Simon

Anon

I assume that you haven't changed the code that calls your function. That's part of the problem.

Your code is currently saying something like this:
// while you can fetch a row
while ($sql = mysql_fetch_array($query)) {
// print category name
echo("$cat_name: ");
// while you can fetch a row
while ($sql = mysql_fetch_array($query)) {
// if the link is different from the last one
if (!old_link == $link) { // your syntax is wrong here*
// print the link
echo(\"<A href=$url>$link</A> . \");
}
}
}

"if (!old_link == $link)" doesn't mean what you think it does. You need to either use parentheses, if (!($old_link == $link)) or the "not equal" operator if ($old_link != $link). And check your code to make sure your variables always start with '$'.

Now to the program logic.

First, you should only have one "mysql_fetch_array($query)" statement in your code. So instead of this:

while ($sql = mysql_fetch_array($query)) {
$cat_name = $sql[\"category_name\"];
echo(\"$cat_name: \");
linklist2();
}

you should just have this:
linklist2();

and print cat name from linklist2().
Or you could just take the code from the function and use it directly. The function should only be called once anyway.

Second, you're on the right track for determining whether a field changes, but you're testing the wrong field. Remember, you want to display a link for every record, but only display category names when the category changes, so you need to test and print $cat_name, not $link.

Also, don't forget to add an "order by category_name" (or "order by category_id") to your SQL. Otherwise your results could look like this:
Search: link link ...
Web: link ..
Search: link ...
Web: link link ..

HTH,
Beth

Anon

I'm afraid my explanation got kind of confusing, so here's pseudo code for the whole page.

Run query

If you can't get the result set
die

While you can fetch the next record from the result set
{
If the category is different from the last one
print category name

Print link

} // Loop back up to While

Notice that there's only one while statement. Also, category name only gets printed when the name changes, but a link gets printed for every record.

HTH,
Beth