sql server - SQL - combine rows conditionally on the value of previous row

Question

My issue I believe is best explained by using an example:

Sample Data

SO	Customer	Product	Description	Quantity	Extension	Country
01	xxx	123	Product A	01	20.00	USA
02	yyy	456	Product B	02	25.00	China
02	yyy	456	Product B	01	12.50	China
02	yyy	789	Product C	01	50.00	Mexico
03	zzz	789	Product C	01	50.00	Mexico
03	zzz	789	Product C	01	50.00	Mexico

question from:https://stackoverflow.com/questions/65847478/sql-combine-rows-conditionally-on-the-value-of-previous-row

Answer 1

This looks like group by:

select SO, Customer, Product, Description, sum(Quantity), sum(Extension),   Country
from t
group by SO, Customer, Product, Description, Country;

Note that quantity looks strange. Numbers in SQL are not shown with leading zeros -- and numbers should be stored as numbers, not strings.