Select max date for each register, null if does not exists - sql

Question

I have these tables: Employee (id, name, number), Configuration (id, years, licence_days), Periods (id, start_date, end_date, configuration_id, employee_id, period_type):
Employee table:
id name number
---- ----- -------
1 Bob 355
2 John 467
3 Maria 568
4 Josh 871
configuration table:
id years licence_days
---- ----- ------------
1 1 8
2 3 16
3 5 24
Periods table:
id start_date end_date configuration_id employee_id period_type
---- ---------- ------- ---------------- ----------- -----------
1 2021-05-23 2021-05-31 1 1 vaccation
2 2021-05-24 2021-06-01 1 2 vaccation
3 2021-03-01 2021-03-17 2 2 vaccation
4 2021-05-05 2021-05-21 2 2 vaccation
5 2021-01-01 2021-01-17 2 4 vaccation
I want this result:
Result:
employee_id years licence_days max(end_date)
1 1 8 2021-05-31
1 3 16 null
1 5 24 null
2 1 8 2021-06-01
2 3 16 2021-05-21
2 5 24 null
3 1 8 null
3 3 16 null
3 5 24 null
4 1 8 null
4 3 16 2021-01-17
4 5 24 null
i.e., I want to select all Employees with all configuration, and for each one of that, the max end_date of the "vaccation" type (or null if it does not exists).
How can I do that

Answer 1

Oracle supports cross joins, right? So may be something like that?
SELECT e.employee_id, c.years, c.licence_days, max(p.end_date)
FROM Employee e
CROSS JOIN configuration c
LEFT JOIN Periods p
ON e.employee_id = p.employee_id
AND c.configuration_id = p.configuration_id
GROUP BY e.employee_id, c.years, c.licence_days
ORDER BY e.employee_id, c.years

Answer 2

#umberto-petrov chooses wisely with the ANSI CROSS JOIN syntax for a cartesian join. However, in the very weak probability that your requires output of configurations even where there is no employees, you can go with something like :
EDIT: Filtering the Periods join with 'vaccation' as asked in the comments.
If you have to filter for some employee ids, change ON 1 = 1 by ON Employee.id IN (id1, id2, ...). It still keeps every configurations but only takes employees that match the ids.
SELECT Employee.employee_id,
Configuration.years,
Configuration.licence_days,
MAX(Configuration.end_date) max_end_date
FROM Configuration LEFT JOIN Employee ON 1 = 1
LEFT JOIN Periods ON Periods.configuration_id = Configuration.id
AND Periods.employee_id = Employee.id
AND Periods.period_type = 'vaccation'
GROUP BY Employee.employee_id,
Configuration.years,
Configuration.licence_days
ORDER BY Employee.employee_id,
Configuration.years,
Configuration.licence_days
We start from configuration to take every records from this one at least, then made a LEFT CARTESIAN JOIN with Employee and finally a full LET JOIN on Periods for both. That way , if there is no employees, this will output configuration_id and NULL for years, licence_days and max end_date.