Compare values of timestamps and assign a value to each of them in case they have changed

Question

DB-Fiddle

CREATE TABLE operations (
    id int auto_increment primary key,
    time_stamp DATE,
    product VARCHAR(255),
    plan_week VARCHAR(2         


        

Answer 1

I would just use window functions:

select o.*,
       (case when min(plan_week) over (partition by product) = max(plan_week) over (partition by product)
             then 'no' else 'yes'
        end) as switched
from operations o;