Querystring for pages (not posts)

Hi to all, i hope that someone can help me to understand better the querystring for pages.

I’ve succesfully used the querystring code showed here in the codex:

$querystr = "
	SELECT * FROM $wpdb->posts
	LEFT JOIN $wpdb->postmeta ON($wpdb->posts.ID = $wpdb->postmeta.post_id)
	LEFT JOIN $wpdb->term_relationships ON($wpdb->posts.ID = $wpdb->term_relationships.object_id)
	LEFT JOIN $wpdb->term_taxonomy ON($wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id)
	LEFT JOIN $wpdb->terms ON($wpdb->terms.term_id = $wpdb->term_taxonomy.term_id)
	WHERE $wpdb->terms.name = 'slides'
	AND $wpdb->term_taxonomy.taxonomy = 'category'
	AND $wpdb->posts.post_status = 'publish'
	AND $wpdb->posts.post_type = 'post'
	AND $wpdb->postmeta.meta_key = 'order'
	ORDER BY $wpdb->postmeta.meta_value ASC
";

Ok, that’s for query the posts, but what i would be glad to know is how to obtain the result with a similar code not for posts but for pages.
The following example, got always from the codex page, is working, but not extensively as the previous:

$querystr = "
    SELECT wposts.*
    FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
    WHERE wposts.ID = wpostmeta.post_id
    AND wpostmeta.meta_key = 'custom-key'
    AND wposts.post_type = 'page'
    ORDER BY wpostmeta.meta_value DESC
    ";

Can someone help me?
Thank you!