Simple query

[eluser]Anonymous[/eluser]
Something tells me this is a stupid question, but i'll ask it anyway

I have a simple table in my db:

Code:

[pages]
  -page_id
  -page_name
  -page_content
  -page_parent_id

Code:

SELECT *
FROM pages
WHERE page_parent_id = $page_name

I want to select all pages where page_parent_id = $page_slug.
Do i have to run 2 querys to get the page_id of the $page_slug given ? Or is this possible in 1 query?