Invalid SQL query in property "orderby"

I am trying to query blog posts on my website using a data source web part.

Using a SQL where clause in my data source I am doing the following to grab by category from the query string:

('{%ToInt(QueryString.categoryid, "")#%}' = 0 AND '{%categoryname%}'='') OR (DocumentID IN (SELECT DocumentID FROM CMS_DocumentCategory WHERE CategoryID = {% ToInt(QueryString.categoryid) #%}))

From there I want to order by BlogPostDate in descending order, so I go into my order by clause in the data source web part and add the following:

ORDER BY BlogPostDate DESC

I am getting an error every single time stating it is an invalid SQL query. How can I make this query work with the where and the order by clause?