SQL join five tables - mysql

Question

I am working on issue, and cannot resolve it.
I have five tables:
t_employee = {employee_id_pk, fullname, phone, position, passport}
t_facility = {facility_id_pk, direction, title}
t_employee_facility = {emp_fac_id_pk, employee_id_fk, facility_id_fk}
this table is #ManyToMany relationship
between 't_employee' and 't_facility'
t_transport = {transport_id_pk, type}
t_trip = {trip_id_pk, trip_code, employee_id_fk, transport_id_fk}
this table is #ManyToMany relationship between 't_employee' and 't_transport'
And I want to get unique rows
I tried something like this
SELECT
employee_id, fullname, passport, phone, position, direction, title,
trip_code
FROM
t_facility
INNER JOIN t_employee_facility USING (facility_id)
INNER JOIN t_employee USING (employee_id)
INNER JOIN t_trip USING (employee_id)
GROUP BY
employee_id,
facility_id,
trip_code
There are 8 uniquie rows.
But the above example gives me 18, when I remove trip_id I get 8 rows, but
in this case I get repeating trip_code values for each employee_id.
I want to extract only not repeating rows. I guess that, I should do it using INNER JOIN, but I'm not sure.
Is it possible to join all this tables ?
thank you
Regards

Answer 1

It can be achieved using nested join query as follow:
SELECT B.employee_id, employee_id, fullname, passport, phone,
position,direction, title, trip_code
FROM (SELECT A.employee_id, employee_id, fullname, passport, phone,
position,direction, title
FROM (SELECT employee_id, direction, title FROM t_facility
JOIN t_employee_facility
ON t_facility.facility_id = t_employee_facility.facility_id
) AS A
JOIN employee ON A.employee_id = employee.employee_id) AS B
JOIN t_trip ON B.employee_id = t_trip.employee_id;

Answer 2

the INNER JOIN keyword selects should have matching values in both tables.
Ex :
SELECT id_pk,information,about
FROM information
INNER JOIN employe ON information.id_pk= employe.id_employe;
So yes, you can join your table when declare it each table.

Answer 3

If you only want the rows to be unique but it is OK, that some employees show more than one facility or trip, you may use the DISTINCT keyword.
SELECT DISTINCT
employee_id,
fullname,
passport,
phone,
position,
direction,
title,
trip_code
FROM t_facility
INNER JOIN t_employee_facility
USING (facility_id)
INNER JOIN t_employee
USING (employee_id)
INNER JOIN t_trip
USING (employee_id);

Answer 4

There are many unclear things in your question, still I'm posting whatever I have figured-out.
First of all I cannot see the table t_employee in FROM clause so I'm not sure this query will work. To get the column values for fullname, passport, phone, position you need to add the relevant table t_employee into FROM clause.
I'm not pretty sure about the JOIN syntax, you can check the MySQL JOINs syntax here.
SELECT
employee_id, fullname, passport, phone, position, direction, title,
trip_code
FROM
t_employee
INNER JOIN t_facility USING (facility_id)
INNER JOIN t_employee_facility USING (facility_id)
INNER JOIN t_employee USING (employee_id)
INNER JOIN t_trip USING (employee_id)
GROUP BY
employee_id,
facility_id,
trip_code
If this still doesn't work, you can try doing SELECT DISTINCT to get unique records, see the syntax here.