Can't access variable in inner scope? - mysql

Question

I'm trying to get this piece of SQL query to work. The problem is that I can't access core_user.id in the stuff in its parameters. I don't really know why.
SELECT
core_user.id AS target, (
SELECT
COUNT(permission_id) AS permissions
FROM (
SELECT
DISTINCT permission_id
FROM (
SELECT
id,
permission_id
FROM
core_user_user_permissions
WHERE
core_user_user_permissions.user_id = core_user.id
UNION
SELECT
id,
permission_id
FROM
auth_group_permissions
WHERE
auth_group_permissions.group_id IN (
SELECT
group_id
FROM
core_user_groups
WHERE
core_user_groups.user_id = core_user.id)) AS `permissions`) AS `derived`) AS `perms`
FROM
`core_user`
WHERE
`core_user`.`is_active` = TRUE
GROUP BY
`core_user`.`id`
ORDER BY
`perms` ASC
If i try target.id with core_user AS target it does not work either: Unknown column 'target.id' in 'where clause'
Expected Results:
+----------------------------------+-------+
| id | perms |
+----------------------------------+-------+
| ab7ec54bf9124dffb807fb89f9ea8036 | 0 |
| b54d4d3f97134dfcbc36ac193c0c1250 | 81 |
| c69ffa4d162b49129ff6a316da3caaa3 | 64 |
| f8ac73eee80044359c246f3b173aa631 | 0 |
+----------------------------------+-------+
Any idea how to fix this?

Answer 1

It's not easy to understand what one wants, if there is only an (invalid) query and no description of what it should retrieve. So this is just a best guess:
SELECT cu.id target,
count(x.permission_id) perms
FROM core_user cu
LEFT JOIN (SELECT cuup.permission_id,
cuup.user_id
FROM core_user_user_permissions cuup
WHERE cuup.permission_id IS NOT NULL
UNION
SELECT agp.permission_id,
cug.user_id
FROM auth_group_permissions agp
INNER JOIN core_user_groups cug
ON cug.group_id = agp.group_id
WHERE agp.permission_id IS NOT NULL) x
ON x.user_id = cu.id
WHERE cu.is_active = TRUE
GROUP BY cu.id
ORDER BY perms ASC;
Instead of getting the count in a subselect it left joins the permission IDs for each user. Grouping by the user ID than gets the (distinct, because the union already removed any duplicates and id is also unique in core_user (I assume)) count of the non null permission IDs of a user, which is what I believe you want.
(You may remove the WHERE <alias>.permission_id IS NOT NULL in the inner query, if there are not null constraints on the columns. The idea here is, that nulls aren't counted in the end anyway, so we want to discard them as early as possible.)
(Untested, as neither schema nor sample data was provided. May contain typos.)

Answer 2

I would rewrite it as:
SELECT core_user.id AS target,
(SELECT COUNT(permission_id) AS permissions
FROM (SELECT permission_id
FROM core_user_user_permissions
WHERE core_user_user_permissions.user_id = `core_user`.id
UNION
SELECT permission_id
FROM auth_group_permissions
WHEREauth_group_permissions.group_id IN (
SELECT group_id
FROM core_user_groups
WHERE core_user_groups.user_id = `core_user`.id)
) AS `derived`
) AS `perms`
FROM `core_user`
WHERE `core_user`.`is_active` = TRUE
GROUP BY `core_user`.`id`
ORDER BY `perms`;
I've removed one level of nested subquery in SELECT list.

Answer 3

Well I hope I could get your expected result by excluding group premissons:
SELECT core_user.id AS target,
(
SELECT COUNT(DISTINCT(permission_id)) AS permissions
FROM
(
SELECT cuup.id as id, cuup.permission_id as permission_id
FROM core_user_user_permissions cuup
-- WHERE cuup.user_id = cu.id
--VV-- this should be a join
JOIN core_user cu ON cu.id = cuup.user_id
)
) AS `perms`
FROM `core_user`
WHERE `core_user`.`is_active` = TRUE
GROUP BY `core_user`.`id`
ORDER BY `perms` ASC