Question

I’m having some difficulty getting to the bottom of this sql query.

Tables:

--Tickets--         --Finance--          --Access--
id_tickets          id_finance           id_access
name_tickets        id_event             id_event
cat_tickets         id_tickets           id_tickets
                    sold_finance         scan_access

Finance and Access both contain a row for multiple of each ticket type as listed in tickets.
and I’m trying to get:

cat_tickets | total_sold | total_scan
-------------------------------------
single      | 3043       | 2571
season      | 481        | 292
comp        | 114        | 75
-------------------------------------
total       | 3638       | 2938

The closest I’ve been to the result I’ve used:

SELECT tickets.cat_tickets, COALESCE(SUM(finance.sold_finance), 0) AS total_sold, COALESCE(SUM(access.scan_access), 0) AS total_scan
FROM finance INNER JOIN tickets ON finance.id_tickets = tickets.id_tickets
INNER JOIN access ON access.id_tickets = tickets.id_tickets
WHERE access.id_event = 235 AND finance.id_event = access.id_event
GROUP BY tickets.cat_tickets
ORDER BY tickets.cat_tickets DESC

but that just returns:

cat_tickets | total_sold | total_scan
-------------------------------------
single      | 4945       | 4437
season      | 954        | 599
comp        | 342        | 375
-------------------------------------
total       | 6241       | 5411

Any ideas where I could be going wrong?
Thanks!

Answer 1

The problem is the relation between access and finance tables, you have to join them. Even if you LEFT JOIN the table the predicate finance.id_event = access.id_event will make it INNER JOIN. As a work around, use UNION like this:

SELECT 
  tickets.cat_tickets, 
  SUM(CASE WHEN a.Type = 'f' THEN num ELSE 0 END) AS total_sold,
  SUM(CASE WHEN a.Type = 'a' THEN num ELSE 0 END) AS total_scan
FROM tickets 
LEFT JOIN
( 
  SELECT 'f' Type, id_tickets, sold_finance num
  FROM finance f
  WHERE id_event = 1
  UNION ALL
  SELECT 'a', id_tickets, scan_access
  FROM access 
  WHERE id_event = 1
) a ON a.id_tickets = tickets.id_tickets
GROUP BY tickets.cat_tickets;

SQL Fiddle Demo