How do I include the matched item from a list in a sub-select?

Question

I'm not sure if I phrased that correctly but here's my dilemma. I inherited an application which needs to look up the company associated with each contact in a list. The way it is currently written the application queries the DB on the following:

SELECT c.name
FROM   company c
WHERE  c.id = (SELECT u.company_id
               FROM   user u
               WHERE  u.login_id = ?);

The problem is that it needs to look up thousands of users so doing this query one at a time is really inefficient. What I'd like to do is run 1 query like this:

SELECT c.name
FROM   company c
WHERE  c.id = (SELECT u.company_id
               FROM   user u
               WHERE  u.login_id IN LIST (?,?,?...));

But I don't know how to then match the list of users back up with the company? How do I get it to select the matched login_id along with the name?

UPDATE: How do I apply the answer below to a more complex query that pulls contract info from another DB? The current full query looks like this (This pulls multiple rows also, one for each active contract level. Eventually I also want to have it combine those into 1 with a list of all contract types so I can then run a grep on that field for the "highest" one (unless there's also a way to do a custom sort in SQL and only return the first one):

SELECT c.id,
       c.name,
       cs.id,
       cs.name,
       csc.contract_type,
       csc.contract_status
FROM   company c,
       company_site cs,
       company_site_contract csc
WHERE  c.id = cs.company_id
       AND cs.id = csq.site_id
       AND csc.contract_status = 'ACTIVE'
       AND cs.site_id IN (SELECT   cs.site_id
                            FROM   user u,
                                   contact c,
                                   company_site cs
                            WHERE  c.id = u.company_id
                                   AND cs.id = c.site_id
                                   AND u.login_id = ?);

Answer 1

select c.name, u.login_id
from company c
inner join user u on u.company_id = c.id
where u.login_id in (List(?,?,?...))

if you have users that are not associated with companies then do this

select c.name, u.login_id
from user u
left join company c on c.id = u.company_id
where u.login_id in (List(?,?,?...))