How to get weekending having all approved records?

I have a table like below

date      |    weekending   |    isapproved

2/17/2020     2/23/2020            0
2/18/2020     2/23/2020            1
2/19/2020     2/23/2020            0
2/20/2020     2/23/2020            0
2/27/2020     3/1/2020             1
2/26/2020     3/1/2020             1
2/28/2020     3/1/2020             1
3/4/2020      3/8/2020             0
3/5/2020      3/8/2020             1
3/5/2020      3/8/2020             1

now want to get weekending ‘3/1/2020’ since it have all 1’s in isApproved like this I want to get list of weekending having all 1’s in isApproved

Answer

You can use aggregation and filter with a having clause:

select weekending
from mytable
group by weekending
having min(isapproved) = 1

This works because isapproved only has 0/1 values. So condition min(isapproved) = 1 actually ensures that there is no 0 value.