I have the following tables:
user
car
dealer
user_metrics
- user_id (FK) (required)
- dealer_id (FK) (can be null)
- car_id (FK) (can be null)
- saved
- .... other columns
A user can save a car or a dealership, when that happens the user_metrics.saved is set to true and the related car_id or dealership_id is set (car_id and dealership_id are exclusive, only one is set for a row).
I want user A to be able to see all users that have saved the same cars / dealerships.
So, if user A has saved car 1, 2,3 and dealership 5,7, I want to get all users that have saved any of those cars / dealerships.
I thought about inner join on user_metrics, but, I am not sure how to write the entire query that would deliver on this.
What query would allow me to get all users that have saved any of the cars/dealerships a certain user has saved?
If I understand as well maybe the below query solve your problem.
First should find a list of user A has been reserved after that should search which of car or dealer used by another user
with user_saved_data as (
select um.*,
u.name,
...
from user_metrics um
inner join user u
on um.user_id = u.id
where um.saved = true
and u.id = $1 -- User id of user 'A' or any username (Or use other column for create custom condition)
)
select usd.name as current_reserved_user,
u.name as reserved_by_user,
d.*,
c.*
from user_metrics um
inner join user u on um.user_id = u.id
left join user_saved_data usd on usd.dealer_id notnull and usd.dealer_id = um.dealer_id
left join user_saved_data usd on usd.car_id notnull and usd.car_id = um.car_id
left join dealer d on um.dealer_id = d.id
left join car c on um.car_id = c.id
Related
I have a bit of a complicated scenario. I have two tables, employee and agency. An employee may or may not have an agency, but if an employee has an agency I want the select clause to check another condition on the agency, but if the employee does not have an agency its fine I want to fetch the employee. I'm not sure how to write the select statement for this. This is what I have come up with so far
select * from employee e left join
agency a on a.id = e.agencyID and a.valid = true;
However the problem with this is that it fetches both employees without agencies which is fine, but it also fetches employees with agencies where a.valid = false. The only option I can think of is to do an union but I'm looking for something more simpler.
A UNION could actually be the solution that performs best, but you can write the query without UNION like this:
select *
from employee e
left join agency a
on a.id = e.agencyID
where coalesce(a.valid, true);
That will accept agencies where valid IS NULL, that is, result rows where the agency part was substituted with NULLs by the outer join.
You want except the condition that both table match(agency.id = employee.agencyID) and also agency.id is false. The following query will express the condition.
SELECT
e.*,
a.*
FROM
employee e
LEFT JOIN agency a ON a.id = e.agencyID
WHERE
NOT EXISTS (
SELECT
1
FROM
agency
WHERE
a.id = e.agencyID
AND a.valid IS FALSE)
ORDER BY
e.id;
*First post: apologies in advance if I left anything out. Please let me know and I'll update!
I’m looking for:
users who have not logged in over 30 days
where the user’s role does not equal ('owner', 'renter', 'manager')
and where the source does not equal 'internal'
I have 3 tables
last_login - has user login info (load_date, current_date, last_login)
user - has info about user being external vs internal (source)
role - which role user has (role_name)
I have to join 3 tables for my WHERE conditions. When I join the 3rd table , my results drop from 300 results to just 10 or so. I've checked the tables and I should get at least 200+ results.
Can anyone tell me what's wrong with my joins?
select u.id, u.username
from user as u
join last_login as ll
on u.username = ll.username
join role as r
on ll.username = r.username
where ll.loaddate = ll.current_date - 1
and ll.lastlogin < ll.current_date - 30
and u.source <> 'INTERNAL'
and r.role_name <> ('Owner', 'Renter', 'Manager')
Looking your query i suppose that you should use NOT IN instead of <>. Also try to use INNER or LEFT JOIN. Something like this for example:
select u.id, u.username
from user as u
left join last_login as ll
on u.username = ll.username
left join role as r
on ll.username = r.username
where ll.loaddate = ll.current_date - 1
and ll.lastlogin < ll.current_date - 30
and u.source NOT LIKE '%INTERNAL%'
and r.role_name NOT IN ('Owner', 'Renter', 'Manager')
I have the following tables:
dealer
id (PK)
car
- id (PK)
- dealer_id (FK)
notes
- car_id (FK)
- dealer_id (FK)
- user_id (FK)
- is_active Bool
I want to be able to select all dealers that I have active notes for. Current model does not store dealer_id on notes and car_id on notes at once. It's an either or.
I can do the queries separately:
select *
from dealer
inner join notes n on dealer.id = n.dealer_id and n.user_id=${userId} and n.is_active=true
and:
select *
from dealer
inner join car c on dealer.id = c.dealer_id
inner join notes n on c.id = n.car_id and n.user_id=${userId} and n.is_active=true
I tried to simply combine the two inner joins in the queries but then the:
inner join car c on dealer.id = c.dealer_id
would sift out what the first query would give me and so I would not get all the dealers I should be getting.
How can I write one query that gives me all the dealers I have active notes for?
I would like not to get duplicate dealers in the result.
You're almost there. What you want is called UNION:
SELECT n.*
FROM
notes AS n
INNER JOIN dealer AS d ON d.id = n.dealer_id
UNION
SELECT n.*
FROM
notes AS n
INNER JOIN car AS c ON c.id = n.car_id
INNER JOIN dealer AS d ON d.id = c.dealer_id
I have a situation where each of the clients has users and each user can access to information about one or more branches.
We also have sys admins who can see everything and in database don't have any sites assigned to them. It just says the user is sys admin, so our system does not restrict the access.
I need to make a database query where I extract the list of branches the user has access to, but if the user is sys admin, I want to extract the list of all branches in the system.
I was trying something like this, but it does not work:
Select sites.name, sites.id
FROM sites
WHERE
sites.id IN (
CASE
WHEN (select u.level FROM users "u" WHERE u.username = 'JohnBrown') ='ROLE_SYSTEM_ADMIN'
THEN
(select id FROM sites)
ELSE
(select s2.id FROM users_have_sites uhs2
left join users u2 ON u2.id = uhs2.user_id
left join sites s2 ON s2.id = uhs2.site_id
where u2.username = 'JonhBrown')
END
)
I am getting this error:
ERROR: more than one row returned by a subquery used as an expression
I think something like this would work for you:
SELECT s.name, s.id
FROM sites s
LEFT JOIN users_have_sites uhs ON uhs.site_id = s.id
LEFT JOIN users u ON u.id = uhs.user_id AND u.username = 'JohnBrown'
WHERE (CASE WHEN (SELECT u.level FROM users WHERE u.username = 'JohnBrown') = 'ROLE_SYSTEM_ADMIN'
THEN TRUE ELSE FALSE END
OR u.id IS NOT NULL);
The LEFT JOINs do not filter out records from the sites table like an INNER JOIN would, so any site that meets either of the conditions in the WHERE clause will be in the result. This means that if your subquery shows that the user is a sys admind or if there is a record for that user and site is found in the users_have_sites table, those sites will be in the result set.
EDIT: Another fairly easy to read solution would be something like this:
SELECT s.name, s.id
FROM sites s,
users_have_sites uhs,
users u
WHERE u.username = 'JohnBrown'
AND (u.level = 'ROLE_SYSTEM_ADMIN'
OR (s.id = uhs.site_id AND u.id = uhs.user_id))
GROUP BY s.name, s.id;
The downside of this query is that it uses implicit joins which are not used very much any more. They are generally seen as an older way of doing things and can be less efficient. This will join all rows of on table to all rows of another table and then all of your filtering (and what you would generally think of as join conditions) are all in the WHERE clause. These typed of joins can be less efficient but this one should not be as the WHERE clause makes sure that only 1 result per site.
I think that this does what you want:
select s.name, s.id
from sites s
inner join users u on u.username = 'JohnBrown'
where
u.level = 'ROLE_SYSTEM_ADMIN'
or exists (
select 1
from users_have_sites uhs
where uhs.site_id = s.id and uhs.user_id = u.id
)
Here is another version of the query that you may find easier to follow (I do):
select s.name, s.id
from users u
inner join sites s
on u.level = 'ROLE_SYSTEM_ADMIN'
or exists (
select 1
from users_have_sites uhs
where uhs.site_id = s.id and uhs.user_id = u.id
)
where u.username = 'JohnBrown'
My sql-fu is not strong, and I'm sure I'm missing something simple in trying to get this working. I have a fairly standard group of tables:
users
-----
id
name
carts
-----
id
user_id
purchased_at
line_items
----------
id
cart_id
product_id
products
--------
id
permalink
I want to get a total count of purchased carts for each user, if that user has purchased a particular product. That is: if at least one of their purchased carts has a product with a particular permalink, I'd like a count of the total number of purchased carts, regardless of their contents.
The definition a purchased cart is when carts.purchased_at is not null.
select
u.id,
count(c2.*) as purchased_carts
from users u
inner join carts c on u.id = c.user_id
inner join line_items li on c.id = li.cart_id
inner join products p on p.id = li.product_id
left join carts c2 on u.id = c2.user_id
where
c.purchased_at is not NULL
and
c2.purchased_at is not NULL
and
p.permalink = 'product-name'
group by 1
order by 2 desc
The numbers that are coming up for purchased_carts are strangely high, possibly related to the total number of line items multiplied by the number of carts? Maybe? I'm pretty stumped at the result. Any help would be greatly appreciated.
This ought to help:
select u.id,
count(*)
from users u join
carts c on c.user_id = u.id
where c.purchased_at is not NULL and
exists (
select null
from carts c2
join line_items l on l.cart_id = c2.id
join products p on p.id = l.product_id
where c2.user_id = u.id and
c2.purchased_at is not NULL
p.permalink = 'product-name')
group by u.id
order by count(*) desc;
The exists predicate is a semi-join.
bool_or is what you need
select
u.id,
count(distinct c.id) as purchased_carts
from
users u
inner join
carts c on u.id = c.user_id
inner join
line_items li on c.id = li.cart_id
inner join
products p on p.id = li.product_id
where c.purchased_at is not NULL
group by u.id
having bool_or (p.permalink = 'product-name')
order by 2 desc