Return multiple rows from multi SELECT subquery - mysql

Question

query
SELECT
(SELECT NAME FROM product_component) AS pcNAME,
(SELECT PROJECT_NAME FROM jira_project) AS jpNAME,
(SELECT FILTER_NAME FROM jira_filter) AS jfNAME
Each SELECT will return an indeterminate number of rows. I get the error Subquery returns more than 1 row. My desired output will be something like this (quick sketch):
=======================================
| pcNAME | jpNAME | jfNAME |
=======================================
| data | data | data |
+------------+------------+-----------+
| data | data | data |
+------------+------------+-----------+
| data | data | data |
+------------+------------+-----------+
| | data | data |
+------------+------------+-----------+
| | data | data |
+------------+------------+-----------+
| | data | |
+------------+------------+-----------+
Each column may produce a different number of rows than the others. So I will want to produce the amount of rows from the max and then blank out the others that don't fill the max number of rows.
NOTE: None of these tables have a shared column so cannot achieve as INNER JOIN
Any ideas on how this can be achieved?

Answer 1

One way to handle this in MySQL to use to variables, union all and aggregation:
SELECT MAX(NAME) as NAME, MAX(PROJECT_NAME) as PROJECT_NAME,
MAX(FILTER_NAME) as FILTER_NAME
FROM ((SELECT (#rnpc := #rnpc + 1) as rn, NAME, NULL as PROJECT_NAME, NULL as FILTER_NAME
FROM product_component CROSS JOIN
(SELECT #rnpc := 0) params
) UNION ALL
(SELECT (#rnpn := #rnpn + 1) as rn, NULL, PROJECT_NAME, NULL as FILTER_NAME
FROM jira_project CROSS JOIN
(SELECT #rnpn := 0) params
) UNION ALL
(SELECT (#rnf := #rnf + 1) as rn, NAME, NULL as PROJECT_NAME, NULL as FILTER_NAME
FROM jira_filter CROSS JOIN
(SELECT #rnf := 0) params
)
) t
GROUP BY rn
ORDER BY rn;