Get parent column in 3rd-level subquery - mysql

Question

How can I get a column from the top-most parent query in a subquery within a subquery? Do I have to pass it like a variable? Here's my code:
SELECT c.in_customer_id,
(
SELECT
group_concat(the_schedule separator '\r\n')
FROM
(
SELECT
concat_ws('\n', 'Route: ', s.route_id, 'Interval: ', s.service_interval, 'Week No.: ', s.week_no, 'Weekdays: ', s.weekdays, 'Start Date: ', s.start_date, 'End Date: ', s.end_date, 'Start Time: ', s.start_time, 'End Time: ', s.end_time, '\n') AS the_schedule
FROM
schedule s
WHERE
s.service_address_id IN
(
SELECT in_customer_address_id
FROM tbl_customer_address a2
WHERE a2.in_customer_id = c.in_customer_id
)
AND s.is_skipped = '0'
GROUP BY
s.service_address_id
) a
)
AS "Schedule"
FROM
tbl_customers c
The response I get is "Error Code: 1054. Unknown column 'c.in_customer_id' in 'where clause'"

Answer 1

As a principle, you want to move the sub-queries in to your FROM clause.
Try something like this...
SELECT
c.in_customer_id,
s.grouped_schedule
FROM
tbl_customers AS c
LEFT JOIN
(
SELECT
in_customer_id,
group_concat(the_schedule separator '\r\n') AS grouped_schedule
FROM
(
SELECT
a.in_customer_id,
a.in_customer_address_id,
concat_ws('\n', 'Route: ', s.route_id, 'Interval: ', s.service_interval, 'Week No.: ', s.week_no, 'Weekdays: ', s.weekdays, 'Start Date: ', s.start_date, 'End Date: ', s.end_date, 'Start Time: ', s.start_time, 'End Time: ', s.end_time, '\n') AS the_schedule
FROM
tbl_customer_address AS a
INNER JOIN
schedule AS s
ON s.service_address_id = a.in_customer_address_id
WHERE
s.is_skipped = 0
)
AS schedules
GROUP BY
in_cusomer_id
)
AS s
ON s.in_customer_id = c.in_customer_id