Using MySQL JSON field to join on a table
Solution 1:
With the help of Feras's comment and some fiddling:
SELECT
u.user_id,
u.user_name,
g.user_group_id,
g.group_name
FROM user u
LEFT JOIN user_group g on JSON_CONTAINS(u.user_groups, CAST(g.user_group_id as JSON), '$')
This appears to work, let me know if there's a better way.
Solution 2:
Funny, I got to the opposite solution compared to Kyle's.
I wrote my query like this:
SELECT
u.user_id,
u.user_name,
g.user_group_id,
g.group_name
FROM user u
LEFT JOIN user_group g on JSON_UNQUOTE(JSON_EXTRACT(u.user_groups, '$')) = g.user_group_id;
It also works, and this solution doesn't need any transforming on the right side of the expression, this could provide a benefit in query optimizing in certain cases.
Solution 3:
For arrays like ["1", "2", "3"] that values are in string type, JSON_SEARCH function is the way for your question:
SELECT
u.user_id,
u.user_name,
g.user_group_id
g.group_name
FROM users u
LEFT JOIN user_group g ON (JSON_SEARCH(u.user_groups, 'one', g.user_group_id))
JSON_CONTAINS function does not return true for integers as candidate parameter:
SELECT JSON_CONTAINS(CAST('["1", "2", "3"]' AS JSON), CAST(1 AS JSON), '$')
returns 0 (false). You need to change it to this:
SELECT JSON_CONTAINS(CAST('["1", "2", "3"]' AS JSON), CAST(CONCAT('"', 1, '"') AS JSON), '$')
But JSON_SEARCH can find the result:
SELECT JSON_SEARCH(CAST('["1", "2", "3"]' AS JSON), 'one', 1)
returns "$[0]" that means "true".