(MySQL) converging & summing two tables by period - mysql

Question

I have two tables.
+----+------------+------------+
| id | pay_date | payment |
+----+------------+------------+
| 1 | 2010-01-01 | 20000 |
| 1 | 2010-01-02 | 30000 |
| 1 | 2010-01-03 | 30000 |
| 1 | 2010-01-06 | 40000 |
| 2 | 2010-01-01 | 10000 |
| 2 | 2010-01-03 | 30000 |
| 2 | 2010-01-06 | 70000 |
+----+------------+------------+
+----+------------+------------+
| id | start_date | end_date |
+----+------------+------------+
| 1 | 2010-01-01 | 2010-01-05 |
| 1 | 2010-01-06 | 2010-01-30 |
| 2 | 2010-01-01 | 2010-01-05 |
| 2 | 2010-01-06 | 2010-01-10 |
+----+------------+------------+
And by converging two tables I want to make below table.
+----+------------+------------+------------+
| id | start_date | end_date | payment |
+----+------------+------------+------------+
| 1 | 2010-01-01 | 2010-01-05 | 80000 |
| 1 | 2010-01-06 | 2010-01-30 | 40000 |
| 2 | 2010-01-01 | 2010-01-05 | 40000 |
| 2 | 2010-01-06 | 2010-01-10 | 70000 |
+----+------------+------------+------------+
This table is sum of payment within fixed period by same id.
How can I make this table?

Answer 1

For the exact data you gave us, we can just join the second table to the first one on the condition that the pay date be between the start and end date in the first table, and that the id values match. But immediately there is an obvious edge case problem here. What happens if a pay date happens to overlap both the start and end dates in the second table? Then it is not clear to which range we should assign that payment. If we just use BETWEEN we will end up double counting the payment.
So in my query below, I make the assumption that a pay date gets assigned if it be greater than or equal to the start date, but strictly less than the end date. This may not be the logic you intend, but you're probably going to have make an assumption similar to this if you ever have overlapping data.
SELECT
t2.id, t2.start_date, t2.end_date, SUM(t1.payment) AS payment
FROM table2 t2
LEFT JOIN table1 t1
ON t1.id = t2.id AND
t1.pay_date >= t2.start_date AND
t1.pay_date < t2.end_date
GROUP BY
t2.id, t2.start_date, t2.end_date
ORDER BY
t2.id, t2.start_date;
Output:
Demo here:
Rextester

Answer 2

Sum up the payment column having pay_date between start_date and end_date in the other table.
Query
select t1.`id`, t1.`start_date`, t1.`end_date`,
sum(t2.`payment`) as `payment`
from `table2` as t1
join `table1` as t2
on t1.`id` = t2.`id`
and t2.`pay_date` between t1.`start_date` and t1.`end_date`
group by t1.`id`, t1.`start_date`, t1.`end_date`;