I need to create a query to define changes in price for different version . For example this is the table :
id | price | date| version
1 | 10 |2020-06-01| 1
1 | 15 |2020-06-12| 2
2 | 4 |2020-06-03| 1
2 | 5 |2020-06-04| 2
2 | 5.5 |2020-06-10| 3
I started to create one query like this :
select t1.price - t2.price from product_price_version t1, product_price_version t2
where t1.version = t2.version - 1
I need to have as results :
id | price | date| version | difference
1 | 10 |2020-06-01| 1 | 0
1 | 16 |2020-06-12| 2 | 6
2 | 4 |2020-06-03| 1 | 0
2 | 5 |2020-06-04| 2 | 1
2 | 5.5 |2020-06-10| 3 | 1.5
in the end to add a filter and to show values where difference is greater than 5
You can use lag():
select
t.*,
price - lag(price, 1, price) over(partition by id order by version) diff
from mytable t
In earlier versions, you can self-join or use a correlated subquery:
select
t.*,
t.price - coalesce(t1.price, t.price) diff
from mytable t
left join mytable t1 on t1.id = t.id and t1.version = t.version - 1