SQL Joining Multiple Tables mySQL - mysql

Question

Hey Guys I need Help with an SQL statement. There are 5 tables total and I need to join multiple tables for a SELECT statement.
These are the tables:
+-----------+------------+------------+
| person_id | first_name | last_name |
+-----------+------------+------------+
| 1 | Tom | Hanks |
| 2 | Anne | Hathaway |
| 3 | Tom | Cruise |
| 4 | Meryl | Streep |
| 5 | Chris | Pratt |
| 6 | Halle | Berry |
| 7 | Robert | De Niro |
| 8 | Julia | Roberts |
| 9 | Denzel | Washington |
| 10 | Melissa | McCarthy |
+-----------+------------+------------+
+-------------+----------------------+
| building_id | building_name |
+-------------+----------------------+
| 1 | Headquarters |
| 2 | Main Street Building |
+-------------+----------------------+
+---------+-------------+-------------+----------+
| room_id | room_number | building_id | capacity |
+---------+-------------+-------------+----------+
| 1 | 100 | 1 | 5 |
| 2 | 200 | 1 | 4 |
| 3 | 300 | 1 | 10 |
| 4 | 10 | 2 | 4 |
| 5 | 20 | 2 | 4 |
+---------+-------------+-------------+----------+
+------------+---------+---------------------+---------------------+
| meeting_id | room_id | meeting_start | meeting_end |
+------------+---------+---------------------+---------------------+
| 1 | 1 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 |
| 2 | 1 | 2016-12-25 10:00:00 | 2016-12-25 12:00:00 |
| 3 | 1 | 2016-12-25 11:00:00 | 2016-12-25 12:00:00 |
| 4 | 2 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 |
| 5 | 4 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 |
| 6 | 5 | 2016-12-25 14:00:00 | 2016-12-25 16:00:00 |
+------------+---------+---------------------+---------------------+
+-----------+------------+
| person_id | meeting_id |
+-----------+------------+
| 1 | 1 |
| 10 | 1 |
| 1 | 2 |
| 2 | 2 |
| 3 | 2 |
| 4 | 2 |
| 5 | 2 |
| 6 | 2 |
| 7 | 2 |
| 8 | 2 |
| 9 | 3 |
| 10 | 3 |
| 1 | 4 |
| 2 | 4 |
| 8 | 5 |
| 9 | 5 |
| 1 | 6 |
| 2 | 6 |
| 3 | 6 |
+-----------+------------+
The problem:
Construct the SQL statement to find all the meetings that Tom Hanks has to attend. Display the following columns:
Person’s first name
Person’s last name
Building name
Room number
Meeting start date and time
Meeting end date and time
My statement:
SELECT person.first_name, person.last_name, building.building_name,
->
-> room.room_number, meeting.meeting_start, meeting.meeting_end
->
-> FROM person
->
-> JOIN building
->
-> ON person.person_id = building.building_id
->
-> JOIN room
->
-> ON person.person_id = room.room_id
->
-> JOIN meeting
->
-> ON person.person_id = meeting.meeting_id
->
-> WHERE person_id = 1;
RESULT:
+------------+-----------+---------------+-------------+---------------------+---------------------+
| first_name | last_name | building_name | room_number | meeting_start | meeting_end |
+------------+-----------+---------------+-------------+---------------------+---------------------+
| Tom | Hanks | Headquarters | 100 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 |
+------------+-----------+---------------+-------------+---------------------+---------------------+
Tom Hanks has multiple meetings.(4 to be exact) How do I show the 4 meetings? Not sure what to do here. It is only showing 1 with my statement.

Answer 1

Was able to find a solution. JOIN was not needed...
SELECT first_name,last_name ,building_name,room_number ,meeting_start,meeting_end
FROM person P, building B,person_meeting PM,meeting M,room R
WHERE
P.person_id=PM.person_id
AND M.room_id=R.room_id
AND B.building_id=R.building_id
AND PM.meeting_id=M.meeting_id
AND P.first_name='Tom'
AND P.last_name='Hanks';

Answer 2

This query should give you what you want (barring any spelling mistakes :P!)
SELECT person.first_name,
person.last_name,
building.building_name,
room.room_number,
meeting.meeting_start,
meeting.meeting_end
FROM person
INNER JOIN person_meeting ON person_meeting.person_id = person.person_id
INNER JOIN meeting ON meeting.meeting_id = person_meeting.meeting_id
INNER JOIN room ON room.room_id = meeting.room_id
INNER JOIN building on building.building_id = room.building_id
WHERE person.person_id = 1
With this query you are joining the tables on the relationships you've created.
A person is linked to meeting via meeting.person_id = person.person_id a meeting is linked to a room via room.room_id = meeting.room_id and a room is linked to a building via building.building_id = room.room_id then finally filtering down these to only show where person.person_id = 1
The issue with your query was you tried to join everything onto person via person_id
JOIN building ON person.person_id = building.building_id
+-------------+----------------------+
| building_id | building_name |
+-------------+----------------------+
| 1 | Headquarters |<-
| 2 | Main Street Building |
+-------------+----------------------+
from this table we will only get building_id = 1
JOIN room ON person.person_id = room.room_id
+---------+-------------+-------------+----------+
| room_id | room_number | building_id | capacity |
+---------+-------------+-------------+----------+
| 1 | 100 | 1 | 5 | <-
| 2 | 200 | 1 | 4 |
| 3 | 300 | 1 | 10 |
| 4 | 10 | 2 | 4 |
| 5 | 20 | 2 | 4 |
+---------+-------------+-------------+----------+
from this table we will only get room_id = 1
JOIN meeting ON person.person_id = meeting.meeting_id
+------------+---------+---------------------+---------------------+
| meeting_id | room_id | meeting_start | meeting_end |
+------------+---------+---------------------+---------------------+
| 1 | 1 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 | <-
| 2 | 1 | 2016-12-25 10:00:00 | 2016-12-25 12:00:00 |
| 3 | 1 | 2016-12-25 11:00:00 | 2016-12-25 12:00:00 |
| 4 | 2 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 |
| 5 | 4 | 2016-12-25 09:00:00 | 2016-12-25 10:00:00 |
| 6 | 5 | 2016-12-25 14:00:00 | 2016-12-25 16:00:00 |
+------------+---------+---------------------+---------------------+
from this table we can see we will only get meeting_id = 1
Primary Keys/Foreign Keys
Person.person_id is your PK and meeting.person_id is your FK
room.room_id is your PK and meeting.room_id is your FK
Building.building_id is your PK and room.building_id is your FK
SQL Fiddle