file 2

SELECT
  mm.`user_id`,
  u.`name`    ,
  mm.`group_id`,
  g.`group_name`,
  p.`party_id`, p.`party_name`,p.`party_cost` , 
 
 @amount_paid := 
 (
 SELECT IF(SUM(product_cost) IS NULL, 0, SUM(product_cost))
 FROM `party_budget_detail` 
 WHERE `party_id`=p.`party_id` AND purchased_by=u.`user_id` 
 ) AS amount_paid,
 
 @member_count := 
 (
 SELECT COUNT(user_id) AS count_ 
 FROM member_management 
 WHERE group_id = mm.`group_id` 
 ) AS member_count,
 
@share_price := p.party_cost/@member_count AS share_price,
@amount_paid - @share_price AS due_amount
 
FROM `member_management` AS  mm INNER JOIN
     `users` AS u
       ON mm.`user_id` = u.`user_id`
    INNER JOIN `group` AS g
      ON mm.`group_id` = g.`group_id`
   INNER JOIN `parties` AS p
     ON p.`group_id` = g.`group_id` 
     WHERE party_id=63 ORDER BY p.party_id;
     

file1

 SELECT
  mm.`user_id`,
  u.`name`    ,
  mm.`group_id`,
  g.`group_name`, , p.`party_name`,p.`party_cost` , 
 
 (
 SELECT IF(SUM(product_cost) IS NULL, 0, SUM(product_cost))
 FROM `party_budget_detail` 
 WHERE `party_id`=p.`party_id` AND purchased_by=u.`user_id` 
 ) AS amount_paid,
 
 amount_paid/5
 
  
FROM `member_management` AS  mm INNER JOIN
     `users` AS u
       ON mm.`user_id` = u.`user_id`
    INNER JOIN `group` AS g
      ON mm.`group_id` = g.`group_id`
   INNER JOIN `parties` AS p
     ON p.`group_id` = g.`group_id` WHERE party_id=63 ORDER BY p.party_id;