I have these columns: type(char), date , price. I would like to check if the same type’s price has not changed in the previous record. I tried this for start: I only want to check for the date prior not for every date that is smaller. This table stores price changes. product_type change_date price &#821…

SQL Server check for prior record only

I have these columns: type(char), date , price. I would like to check if the same type’s price has not changed in the previous record.

I tried this for start:

SELECT *
FROM table t1, table t2
WHERE t1.date > t2.date and t1.type = t2.type

I only want to check for the date prior not for every date that is smaller.

This table stores price changes.

I want to put this table next to it self to see if the price remained unchanged like this:

product_type	change_date	price	product_type	change_date	price
‘A’	2020.02.20	750	‘A’	2020.02.18	500
‘A’	2020.02.22	800	‘A’	2020.02.20	750
‘B’	2020.02.27	900	‘B’	2020.02.22	500
‘C’	2020.02.29	700	‘C’	2020.02.22	400

I only want to display rows that show no price change, so price = previous price.

Try this:

select 
    t.*, 
    lag(price) over(partition by type order by date) as previous_price 
from table t