MySQL group_concat and nest with another group_concat - php

Question

Not sure if the title explains the situation right but I will try to do my best explaining here.
I have a table with 3 fields linked to other tables and I want to get all the Rows grouped in the following way:
item_id, user_id, group_id
1 2 3
2 2 3
3 4 5
4 2 4
In my query i want in comma separated format all the items_id grouped by group_id i also have some extra conditions on the WHERE clause that's why the inner join
That i can do like with this query
"SELECT
GROUP_CONCAT( DISTINCT A.item_id ) AS ids
FROM tableA A
INNER JOIN tableB B ON(tableA.id = tableB.id)
WHERE xxxxx
GROUP BY A.group_id
"
Later i can loop the results and using the comma separated to inner loop every id within the result
But i also want to group it by user_id in order to do something like this
foreach( query_results.... ){
foreach( group_id.... ){
foreach( item_id.... ){
// Display info
}
}
}
Any ideas on this?

Answer 1

using subqueries, we can get both itemids, userids as two seperate columns
select T1.group_id, T1.itemids, T2.userids
FROM
(SELECT group_id,
GROUP_CONCAT( DISTINCT A.item_id ) AS itemids
FROM table1 A
group by group_id) T1
INNER JOIN
(
SELECT
group_id, GROUP_CONCAT( DISTINCT A.user_id ) AS userids
FROM table1 A
group by group_id
) T2
on T1.group_id = T2.group_id

Answer 2

Use 2 GROUP_CONCATS
SELECT GROUP_CONCAT( DISTINCT A.item_id ) AS ids,
GROUP_CONCAT( DISTINCT A.group_id ) AS groups
FROM tableA A
INNER JOIN tableB B ON(tableA.id = tableB.id)
WHERE xxxxx
GROUP BY A.group_id
Loop your resource then use Explode on the groups and ids value and loop them both as you want