Hi,
I m a new SQL leaner, and got my self into a difficult question,
let's say i have this table:
- create table purchase(
-
datePurchase date
-
itemiId int,
-
nbItemSold int
-
cstmrId int
-
);
How can I get the daily difference of the product sold ?
Ex:
-
insert into purchase values
-
('2017-02-01' ,4, 'product1'),
-
('2017-02-01', 3, 'product2'),
-
('2017-02-01', 1, ' product3'),
-
('2017-02-02', 1, 'product1'),
-
('2017-02-02', 2, 'product2'),
-
('2017-02-02', 1, 'product3'),
-
('2017-02-03', 5, 'product2'),
-
('2017-02-03', 1, 'product3'),
-
('2017-02-03', 0, 'product1');
-
Query result would be (getting the difference between the number of the product sold on the D day with those sold on the D-1 day):
the final table resulting of these difference should contain this datas
2017-02-02, product1, -3
2017-02-02, product2, -1
2017-02-02, product3, 1
2017-02-03, product1, -1
2017-02-03, product2, 3
2017-02-03, product3, 0
the customer doesn't matter. i just want to find the daily difference in selling products
