How can I combine these two queries into one?

[brooksh]

How can I combine these two queries then how do I display the results?

 

First I need to grab my main category

SELECT DISTINCT category_name,category_id FROM db WHERE parent_id ='0' Order By category_name

Then I need to grab the subcategories with the $category_id from the main category

SELECT DISTINCT category_name,category_id FROM db WHERE parent_id = '$category_id' Order By category_name

[Muddy_Funster]

you could try

 SELECT DISTINCT category_name, catagory_id FROM db WHERE parent_id IN (0, (SELECT catagory_id FROM db as dbTemp WHERE parent_id = 0))