Change json field in mysql to include data from other table - mysql

Question

I have these two tables:
CREATE TABLE `config_support_departments` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`title` varchar(200) NOT NULL DEFAULT '',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `support_tickets_filters` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`filter_departments` json DEFAULT NULL,
PRIMARY KEY (`id`),
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
config_support_departments:
+----+-------------------------+
| id | title |
+----+-------------------------+
| 1 | Projects / File Support |
| 2 | Sales Support |
| 3 | IT Support |
+----+-------------------------+
support_tickets_filters:
+----+--------------------+
| id | filter_departments |
+----+--------------------+
| 1 | ["2", "3"] |
+----+--------------------+
What I need is when query the support_tickets_filters table to also include the title from the config_support_departments table. Hence, the result should be something like this:
+----+-----------------------------------------------+
| id | filter_departments |
+----+-----------------------------------------------+
| 1 | {"2":"Sales Support","3":"IT Support"} |
+----+-----------------------------------------------+

Answer 1

You can use JSON_OBJECTAGG() function along with JSON_TABLE() if DB version is 8.0+
SELECT s.id, JSON_OBJECTAGG(c.id,c.title) AS filter_departments
FROM `support_tickets_filters` AS s
JOIN JSON_TABLE(
s.`filter_departments`,
'$[*]' COLUMNS (id INT PATH '$')
) j
JOIN `config_support_departments` AS c
ON j.id = c.id
GROUP BY s.id
For DB version 5.7, you can use one of the DB metadata tables such as information_schema.tables in order to generate index values as 0,1,... upto the length of the array (filter_departments) for extracting the related value from that iteratively
SELECT s.id, JSON_OBJECTAGG(c.id,c.title) AS filter_departments
FROM
(
SELECT #i := #i + 1 AS n, s.id,
JSON_UNQUOTE(JSON_EXTRACT(`filter_departments`,CONCAT('$[',#i,']'))) AS elm
FROM `support_tickets_filters` AS s
JOIN (SELECT #i := -1) AS iter
LEFT JOIN information_schema.tables AS t
ON #i < JSON_LENGTH(`filter_departments`) - 1 ) AS s
JOIN `config_support_departments` AS c
ON s.elm = c.id
GROUP BY s.id
Demo