calculate 2 days prior and 2 days after sales - mysql

Question

wants to calculate 2 days prior and 2 days after sales
total_2_days_prior_sales = before 2 days to current date sales sum
total_2_days_prior_sales = from current date to next 2 days sales sum
Requirement:
Live Code:
http://sqlfiddle.com/#!9/d88bee/15
My Try:
CREATE TABLE test (
end_date date,
sales int
);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-01',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-01',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-02',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-02',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-03',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-04',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-05',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-06',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-07',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-08',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-08',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-09',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-10',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-11',10);
INSERT INTO test (end_Date, sales)
VALUES ('2022-01-12',10);
Code:
select
end_Date,
-- DATE_SUB(date(end_Date), INTERVAL 2 day),
-- DATE_SUB(date(end_Date), INTERVAL -2 day),
-- DATE_SUB(date(end_Date), INTERVAL 0 day),
SUM(sales) as CurrentSales,
SUM(case when end_Date between DATE_SUB(date(end_Date), INTERVAL 2 day) and DATE_SUB(date(end_Date), INTERVAL 0 day) then sales else 0 end) total_2_days_prior_sales,
SUM(case when end_Date between DATE_SUB(date(end_Date), INTERVAL 0 day) and DATE_SUB(date(end_Date), INTERVAL -2 day) then sales else 0 end) total_2_days_after_sales
from test
group by end_Date

Answer 1

Since MySQL 5.6 does not support window functions and CTE, you can use subqueries to get the totals for prior sales and after sales, like this
SELECT
*,
(SELECT SUM(t.sales)
FROM test t
WHERE t.end_date BETWEEN DATE_SUB(s.end_Date, INTERVAL 1 day) AND s.end_date
GROUP BY s.end_date) total_2_days_prior_sales,
(SELECT SUM(t.sales)
FROM test t
WHERE t.end_date BETWEEN s.end_date AND DATE_ADD(s.end_Date, INTERVAL 1 day)
GROUP BY s.end_date) total_2_days_after_sales
FROM (
SELECT
end_Date,
SUM(sales) CurrentSales
FROM test
GROUP BY end_Date
) s
Output
end_Date
CurrentSales
total_2_days_prior_sales
total_2_days_after_sales
2022-01-01
20
20
40
2022-01-02
20
40
30
2022-01-03
10
30
20
2022-01-04
10
20
20
2022-01-05
10
20
20
2022-01-06
10
20
20
2022-01-07
10
20
30
2022-01-08
20
30
30
2022-01-09
10
30
20
2022-01-10
10
20
20
2022-01-11
10
20
20
2022-01-12
10
20
10
If to change the interval from 2 days to 3 days, output is like this
end_Date
CurrentSales
total_3_days_prior_sales
total_3_days_after_sales
2022-01-01
20
20
50
2022-01-02
20
40
40
2022-01-03
10
50
30
2022-01-04
10
40
30
2022-01-05
10
30
30
2022-01-06
10
30
40
2022-01-07
10
30
40
2022-01-08
20
40
40
2022-01-09
10
40
30
2022-01-10
10
40
30
2022-01-11
10
30
20
2022-01-12
10
30
10
You can check a sqlfiddle here
Also you can use a self JOIN with your table and calculate sub totals conditionally like this
SELECT
s.end_date,
s.sales,
SUM(CASE WHEN t.end_date <= s.end_date
THEN t.sales
END) prev_sales,
SUM(CASE WHEN t.end_date >= s.end_date
THEN t.sales
END) after_sales
FROM (
SELECT
end_date,
SUM(sales) sales
FROM test
GROUP BY end_date
) s
JOIN test t ON t.end_date BETWEEN DATE_SUB(s.end_Date, INTERVAL 1 day) AND DATE_ADD(s.end_Date, INTERVAL 1 day)
GROUP BY end_date
This query produces the same output.
You can check it here
In general, a join should perform better.
Also you need a composite index on the end_date and sales columns in your table.