[cinq's vbArticles v1.0 Hack] - The development process

[rake]

Originally Posted by cinq

Problem Number 2

I implemented a 'Previous article Next article' feature at the top of each article page which provides an easy means to quickly navigate to another article.

This is the code currently in place:

PHP Code:

# previous and next article links
$nextone = $artid+1;
$chknextonequery = $DB_site->query("SELECT articles_articleid FROM " . TABLE_PREFIX . "articles_article WHERE articles_articleid=$nextone");
if($DB_site->num_rows($chknextonequery)>0)
    {
        $nextarticle = 1;
    }
else
    {
        $nextarticle = 0;
    }

$previousone = $artid-1;
$chkpreonequery = $DB_site->query("SELECT articles_articleid FROM " . TABLE_PREFIX . "articles_article WHERE articles_articleid=$previousone");
if($DB_site->num_rows($chkpreonequery)>0)
    {
        $prearticle = 1;
    }
else
    {
        $prearticle = 0;
    } 


The template where it appears :

<span class="smallfont" style="float:$stylevar[right]">
<if condition="$prearticle==1">
<a href="articles.php?$session[sessionurl]action=viewarticle&artid=$previousone">< Previous Article</a></if>
<if condition="$nextarticle==1 && $prearticle==1">
&nbsp;&nbsp;|&nbsp;&nbsp;
</if>
<if condition="$nextarticle==1">
<a href="articles.php?$session[sessionurl]action=viewarticle&artid=$nextone">Next Article ></a></if>
</span>

Now this code works fine, BUT it assumes that all the rows in the database for articles are present in running order. eg. articleid=1,2,3,4....,100.. It presents a problem when there is a missing articleid in between. for eg. articleid=1,2,3,5,8,10,...,100...

How can I change things to make this work ?
Also if possible combine queries ?

if($next = $DB_site->query_first("SELECT whatever FROM table WHERE articles_articleid > $artid ORDER BY artid ASC"))
{
$nextarticle = 1;
}

if($previous = $DB_site->query_first("SELECT whatever FROM table WHERE articles_articleid < $artid ORDER BY artid DESC"))
{
$prearticle = 1;
}


TADA!