Question

When I retrieve articles information from a mysql database I got an array like this:

Array
(
    [0] => Array
        (
            [CategoryID] => 3
            [CategoryName] => Test Category
            [Parent] => 0
            [Thumb] => 0
            [sort] => 8
            [ArticleID] => 2
            [ArticleCatgories] => 9,4,3
            [ArticleTitle] => vxcvxcvx
            [ArticleBody] => xcvxcvxcvxcv
            [InGroup] => 0
            [GroupID] => 0
            [Published] => 1
            [PublishTime] => 
            [TermID] => 11
            [TermSlug] => xcvxcvxcv
            [RelatedID] => 2
            [TermType] => article
        )

    [1] => Array
        (
            [CategoryID] => 4
            [CategoryName] => Test Image
            [Parent] => 0
            [Thumb] => 0
            [sort] => 4
            [ArticleID] => 2
            [ArticleCatgories] => 9,4,3
            [ArticleTitle] => vxcvxcvx
            [ArticleBody] => xcvxcvxcvxcv
            [InGroup] => 0
            [GroupID] => 0
            [Published] => 1
            [PublishTime] => 
            [TermID] => 11
            [TermSlug] => xcvxcvxcv
            [RelatedID] => 2
            [TermType] => article
        )

    [2] => Array
        (
            [CategoryID] => 9
            [CategoryName] => Test Images
            [Parent] => 0
            [Thumb] => 7
            [sort] => 2
            [ArticleID] => 2
            [ArticleCatgories] => 9,4,3
            [ArticleTitle] => vxcvxcvx
            [ArticleBody] => xcvxcvxcvxcv
            [InGroup] => 0
            [GroupID] => 0
            [Published] => 1
            [PublishTime] => 
            [TermID] => 11
            [TermSlug] => xcvxcvxcv
            [RelatedID] => 2
            [TermType] => article
        )
} 

And because the article is in more than one category, it retrieve the article information more than once.
What I need to do is to combine the category names into a sub array if they have the same ArticleID so the result become like:

Array
(
    [0] => Array
        (
            [CategoryName] => array('Test Category','Test Image','Test Images');
            [Parent] => 0
            [Thumb] => 0
            [sort] => 8
            [ArticleID] => 2
            [ArticleCatgories] => 9,4,3
            [ArticleTitle] => vxcvxcvx
            [ArticleBody] => xcvxcvxcvxcv
            [InGroup] => 0
            [GroupID] => 0
            [Published] => 1
            [PublishTime] => 
            [TermID] => 11
            [TermSlug] => xcvxcvxcv
            [RelatedID] => 2
            [TermType] => article
        )
}

Answer 1

You can build a new array using ArticleID as the keys:

$final = array();
foreach ($rows as $row) {
    $id = $row['ArticleID'];
    if (isset($final[$id])) {
        // we've already seen this article
        // append to categoryname array
        $final[$id]['CategoryName'][] = $row['CategoryName'];
    } else {
        // this is the first article occurrence
        // turn categoryname into array first
        $row['CategoryName'] = array($row['CategoryName']);
        $final[$id] = $row;
    }
}

print_r($final);

Output based on your question:

Array
(
    [2] => Array
        (
            [CategoryID] => 3
            [CategoryName] => Array
                (
                    [0] => Test Category
                    [1] => Test Image
                    [2] => Test Images
                )

            [Parent] => 0
            [Thumb] => 0
            [sort] => 8
            [ArticleID] => 2
            [ArticleCatgories] => 9,4,3
            [ArticleTitle] => vxcvxcvx
            [ArticleBody] => xcvxcvxcvxcv
            [InGroup] => 0
            [GroupID] => 0
            [Published] => 1
            [PublishTime] =>
            [TermID] => 11
            [TermSlug] => xcvxcvxcv
            [RelatedID] => 2
            [TermType] => article
        )

)