Count of other rows in table with the same value

Question

So I\'m a bit new to mySQL and can figure out how to do this. I have a table with columns for worker, the building they work in, and the office they work in.

I\'m tr

Answer 1

Try this:

SELECT t1.*,
  (SELECT COUNT(1)
  FROM mytable t2
  WHERE t2.`room number` = t1.`room number`
  )
FROM mytable t1

I advice you don't use field name with white space, use the underscore instead white space.

Answer 2

These sort of problems are solved with analytic functions.

So have a look at here about analytic functions.

What you need here is to use count(*) over as follows;

select  t.*, count(1) OVER (PARTITION BY office_building, room_number) from t

EDIT

Sorry, just noticed you are working on MYSQL, seems like no analytical functions available on MYSQL

So try this;

   select t.*, wcounts.worker_count 
   from t,
   (select office_building, room_number count(1) as worker_count
      from t
     group by office_building, room_number) wcounts
   where t.office_building = wcounts.office_building
   and t.room_number = wcounts.room_number