How to emulate JSON_OVERLAPS function on MySQL 5.7? - mysql

Question

I have two columns from different tables that hold JSON-formatted data. The data stored in both columns are arrays. Example:
users
+----+------------------+
| id | options |
+----+------------------+
| 1 | ["AB","CD","XY"] |
| 2 | ["CD","GH"] |
+----+------------------+
items
+----+-------------+
| id | options |
+----+-------------+
| 10 | ["CD","EF"] |
| 11 | ["GH","XY"] |
| 12 | ["GH"] |
+----+-------------+
I wanted to write a query that returns all the rows from users which matches a given row from items, using options columns to perform the match. The rule is if any value in the array is present in both rows, they are a match. Example: user 1 would match items 10 (because of CD option) and 11 (because of XY option); user 2 would match items 10, 11 and 12 because all of them have CD or GH.
Looking at MySQL docs I found that JSON_OVERLAPS does exactly that. However, I'm running MySQL 5.7 and the function is only available starting at 8.0.17. There is also no much talking around this function on the web.
How could I emulate JSON_OVERLAPS behavior on MySQL 5.7 in a query?
Edit: Unfortunately, upgrading to MySQL 8 is not an option since we run MariaDB on production, which also doesn't have that function.

Answer 1

How to emulate JSON_OVERLAPS function on MySQL 5.7?
Edit: Unfortunately, upgrading to MySQL 8 is not an option since we run MariaDB on production, which also doesn't have that function.
Be warned like Strawberry, suggested already upgrading is more easy
Now that is out off the way. You still asked for it, lets have some fun.
I posted some answers in the past to simulate MySQL's 8 JSON_TABLE(), why did i mention this? Because i use this method to emulate MySQL's 8 JSON_OVERLAPS to simply JOIN both resultsets which emulate JSON_TABLE() to a final resultset
Which makes the query below (forgive the formatting)
Query
SELECT
*
FROM (
SELECT
items.id
, JSON_UNQUOTE(
JSON_EXTRACT(items.options, CONCAT('$[', number_generator.number , ']'))
) AS json_options
FROM (
SELECT
#items_row := #items_row + 1 AS number
FROM (
SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) row1
CROSS JOIN (
SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) row2
CROSS JOIN (
SELECT #items_row := -1
) init_user_params
) AS number_generator
CROSS JOIN (
SELECT
items.id
, items.options
, JSON_LENGTH(items.options) AS json_array_length
FROM
items
) AS items
WHERE
number BETWEEN 0 AND json_array_length - 1
) AS items
INNER JOIN (
SELECT
users.id
, JSON_UNQUOTE(
JSON_EXTRACT(users.options, CONCAT('$[', number_generator.number , ']'))
) AS json_options
FROM (
SELECT
#users_row := #users_row + 1 AS number
FROM (
SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) row1
CROSS JOIN (
SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) row2
CROSS JOIN (
SELECT #users_row := -1
) init_user_params
) AS number_generator
CROSS JOIN (
SELECT
users.id
, users.options
, JSON_LENGTH(users.options) AS json_array_length
FROM
users
) AS users
WHERE
number BETWEEN 0 AND json_array_length - 1
) AS users
USING(json_options)
Result
| json_options | id | id |
| ------------ | --- | --- |
| CD | 10 | 2 |
| CD | 10 | 1 |
| GH | 11 | 2 |
| GH | 12 | 2 |
| XY | 11 | 1 |
see demo