MySQL select two columns multiple name value pair - mysql

Question

I need help about generating query for multiple column.
part of my tbl_advert_specific_fields_values table look like:
id advert_id field_name field_value
1 654 t1_sqft 50
2 655 t1_yearbuilt 1999
3 1521 t2_doorcount 5
4 656 t1_yearbuilt 2001
5 656 t1_sqft 29
6 654 t1_yearbuilt 2004
SELECT p.*, p.id AS id, p.title AS title, usr.id as advert_user_id,
p.street_num, p.street,c.icon AS cat_icon,c.title AS cat_title,c.title AS cat_title,
p.description as description,
countries.title as country_name,
states.title as state_name,
date_FORMAT(p.created, '%Y-%m-%d') as fcreated
FROM tbl AS p
LEFT JOIN tbl_advertmid AS pm ON pm.advert_id = p.id
INNER JOIN tbl_usermid AS am ON am.advert_id = p.id
LEFT JOIN tbl_users AS usr ON usr.id = am.user_id
INNER JOIN tbl_categories AS c ON c.id = pm.cat_id
INNER JOIN tbl_advert_specific_fields_values AS asfv ON asfv.advert_id = p.id
LEFT JOIN tbl_countries AS countries ON countries.id = p.country
LEFT JOIN tbl_states AS states ON states.id = p.locstate
WHERE p.published = 1 AND p.approved = 1 AND c.published = 1
AND (asfv.field_name = 't1_yearbuilt'
AND CONVERT(asfv.field_value,SIGNED) <= 2004 )
AND (asfv.field_name = 't1_sqft'
AND CONVERT(asfv.field_value,SIGNED) <= 50)
AND p.price <= 10174945 AND (p.advert_type_id = 1)
AND (c.id = 43 OR c.parent = 43)
GROUP BY p.id
ORDER BY p.price DESC
ok, the problem is in this asfv query part that are generated dynamically. It belong to objects which represent adverts by its specific fields. asfv is actually advert_specific_fields_values table (table name say all about it).
Without part:
AND (asfv.field_name = 't1_yearbuilt'
AND CONVERT(asfv.field_value,SIGNED) <= 2004 )
AND (asfv.field_name = 't1_sqft'
AND CONVERT(asfv.field_value,SIGNED) <= 50)
query return all adverts that belong on advert_type_id and price of them are less than 10.174.945,00 €.
All what I need is query update that return only adverts, for example t1_yearbuilt less than 2005 and t1_sqft less than 51 (advert_id => 654,656).
I also need query for values between for example t1_sqft >=30 AND t1_sqft <=50 (advert_id => 654).
Can anybody know how, update this query?
TNX