How to use GROUP_CONCAT on multiple JOIN

Question

I am currently retrieving data from multiple tables using a cus_id as the initial query. From here I have multiple tables that can have various rows of data that I would like to retrieve and use GROUP_CONCAT to return this data in a single row. At the moment, my query is returning duplicate data based on the max number of rows returned by one of the group concats.

SELECT a.id,c.x,c.y,c.z

GROUP_CONCAT(a.column_a) AS aca, 
GROUP_CONCAT(a.column_b) AS acb, 
GROUP_CONCAT(b.column_a) AS bca, 
GROUP_CONCAT(b.column_b) AS bcb, 

FROM `table_a` a
INNER JOIN `table_b` b ON a.id = b.id
INNER JOIN `table_c` c ON a.id = c.id
WHERE a.id = ? 

Also, in this scenario, what is the correct join method to use. I am expecting all the fields I am requesting to have some sort of data.

Answer 1

Problem was resolved by using sub queries to isolate the GROUP_CONCAT requests. This allowed me to get only the data I wanted without duplicate results manipulated by other JOIN requests.

SELECT a.id,c.x,c.y,c.z 

(SELECT GROUP_CONCAT(column_a) FROM table_a) AS aca, 
(SELECT GROUP_CONCAT(column_b) FROM table_a) AS acb, 
(SELECT GROUP_CONCAT(column_a) FROM table_b) AS bca, 
(SELECT GROUP_CONCAT(column_b) FROM table_b) AS bcb,

FROM table_a a
INNER JOIN `table_c` c ON a.id = c.id
WHERE a.id = ? 

Answer 2

Aggregate before joining. Somthing along the lines of:

select
  a.*,
  b.grp_a,
  b.grp_b,
  c.grp_x,
  b.grp_y
from table_a a
join
(
  select
    a_id,
    group_concat(a order by b_id) as grp_a,
    group_concat(b order by b_id) as grp_b
  from table_b
  group by a_id
) b on b.a_id = a.id
join
(
  select
    a_id,
    group_concat(x order by c_id) as grp_x,
    group_concat(y order by c_id) as grp_y
  from table_c
  group by a_id
) c on c.a_id = a.a_id
order by a.a_id;