PHP MySQL count events per location per user - php

Question

I'm trying to build a query using data from 4 tables: Bookings, Users, Events, Locations
Bookings :
+---------------------------------+
|book_id | event_id | person_id |
+---------------------------------+
|1 | 1 | 2 |
|2 | 2 | 1 |
|3 | 2 | 2 |
|4 | 1 | 3 |
|5 | 3 | 1 |
|6 | 3 | 2 |
+---------------------------------+
Users :
+----------------------+
| user_id | name |
+----------------------+
| 1 | Joe |
| 2 | Jack |
| 3 | Jane |
+----------------------+
Events :
+------------------------+
| event_id | location_id |
+------------------------+
| 1 | 1 |
| 2 | 3 |
| 3 | 1 |
+------------------------+
Locations :
+---------------------------+
| location_id | name |
+---------------------------+
| 1 | Lombard |
| 2 | NYC |
| 3 | LA |
+---------------------------+
The query that I can't seem to write should get me to display a table like this :
+------------------------------+
+Name |Lombard|NYC|LA|Total|
+------------------------------+
+Joe |1 |0 |1 |2 |
+Jack |2 |0 |1 |3 |
+Jane |1 |0 |0 |1 |
+------------------------------+
+Totals |4 |0 |2 |6 |
+------------------------------+
What I got to work is displaying how many booking have been made per user but not per user AND per location using this query:
$query='
SELECT
bookings.person_id,
COUNT(bookings.person_id) AS total,
bookings.event_id,
users.display_name
FROM bookings
INNER JOIN users ON bookings.person_id=users.id
WHERE users.id=bookings.person_id
GROUP BY bookings.person_id';
$result = mysql_query($query);
if($result) {
while($row = mysql_fetch_array($result))
{
/* total bookings per user */
$value = $row['total'];
$sum += $value;
/* Displaying results */
echo "<tr width='500'>";
echo "<td>".$row['person_id']."</td>";
echo "<td>".$row['display_name']."</td>";
echo "<td>".$row['total']."</td>";
echo "</tr>";
}
This works okay and displays :
+-----------------------------------+
| ID | NAME | Total Bookings |
+-----------------------------------+
| 7 | Bob | 3 |
| 5 | Jane | 2 |
| 3 | Joe | 1 |
+-----------------------------------+
Could you please help me getting there. Thanks.

Answer 1

You are looking for a pivot table style query. Here's one way you can do it.
select u.name,
count(case when l.name = 'Lombard' then 1 end) as lombard,
count(case when l.name = 'NYC' then 1 end) as nyc,
count(case when l.name = 'LA' then 1 end) la,
count(u.name) total
from bookings b
inner join events e
on b.event_id = e.event_id
inner join locations l
on e.location_id = l.location_id
inner join users u
on u.user_id = b.person_id
group by u.name
with rollup
fiddle here
It gets a lot harder (and is generally easier to do in the application) if you dont know the possible column (location) values when you are writing the query.

Answer 2

http://sqlfiddle.com/#!9/92d50
SELECT u.name,
SUM(l.name = 'Lombard') lombard,
SUM(l.name = 'NYC') nyc,
SUM(l.name = 'LA') la,
COUNT(*) total
FROM bookings b
LEFT JOIN `events` e
ON b.event_id = e.event_id
LEFT JOIN locations l
ON e.location_id = l.location_id
LEFT JOIN users u
ON u.user_id = b.person_id
GROUP BY u.name
WITH ROLLUP