problem with where clause

Here is my query(It is part of a search script and is dynamicly generated): select 0 + article_keyword.weight * article_keyword.keyword like '%green%' as score, article_keyword.aid, article_data.name, article_data.time, article_data.description from article_keyword, article_data where score > 0 and article_data.aid = article_keyword.aid group by article_data.aid order by score desc when I do the query in PHP I get a message saying: Unknown column 'score' in 'where clause'. How can I fix this? -- JJ Harrison webmaster@tececo.com www.tececo.com