MySQL 5.7

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/* table returned */
CREATE TABLE returned (
    id int auto_increment primary key,
    customerID VARCHAR(255),
    returned_date DATE
);

INSERT INTO returned
(customerID, returned_date
)
VALUES 
("Customer_01", "2020-03-20"),
("Customer_01", "2020-03-22"),
("Customer_01", "2020-04-19"),
("Customer_02", "2020-08-09"),
("Customer_03", "2020-07-31"),
("Customer_03", "2020-08-25"),
("Customer_04", "2020-09-16"),
("Customer_04", "2021-09-25");


/* table customers */
CREATE TABLE customers (
    id int auto_increment primary key,
    customerID VARCHAR(255),
    first_order DATE
);

INSERT INTO customers
(customerID, first_order
)
VALUES 
("Customer_01", "2020-03-15"),
("Customer_02", "2020-06-16"),
("Customer_03", "2020-07-27"),
("Customer_04", "2020-08-10");


SELECT
r.customerID,
r.returned_date,
c.first_order,
COUNT(distinct r.customerID)
FROM returned r
JOIN customers c ON c.customerID = r.customerID
WHERE returned_date BETWEEN "2020-01-01" AND "2020-12-31"
AND first_order BETWEEN "2020-01-01" AND "2020-12-31"
GROUP BY 1,2,3;


customerID
returned_date
first_order
COUNT(distinct r.customerID)


Customer_01
2020-03-20
2020-03-15
1

Customer_01
2020-03-22
2020-03-15
1

Customer_01
2020-04-19
2020-03-15
1

Customer_02
2020-08-09
2020-06-16
1

Customer_03
2020-07-31
2020-07-27
1

Customer_03
2020-08-25
2020-07-27
1

Customer_04
2020-09-16
2020-08-10
1


SELECT
r.customerID,
r.returned_date,
c.first_order,
(r.returned_date = c.first_order) is_first_order
FROM returned r
INNER JOIN customers c ON c.customerID = r.customerID


customerID
returned_date
first_order
is_first_order


Customer_01
2020-03-20
2020-03-15
0

Customer_01
2020-03-22
2020-03-15
0

Customer_01
2020-04-19
2020-03-15
0

Customer_02
2020-08-09
2020-06-16
0

Customer_03
2020-07-31
2020-07-27
0

Customer_03
2020-08-25
2020-07-27
0

Customer_04
2020-09-16
2020-08-10
0

Customer_04
2021-09-25
2020-08-10
0

customerID	returned_date	first_order	COUNT(distinct r.customerID)
Customer_01	2020-03-20	2020-03-15	1
Customer_01	2020-03-22	2020-03-15	1
Customer_01	2020-04-19	2020-03-15	1
Customer_02	2020-08-09	2020-06-16	1
Customer_03	2020-07-31	2020-07-27	1
Customer_03	2020-08-25	2020-07-27	1
Customer_04	2020-09-16	2020-08-10	1