SQL select all rows where at least one column is not NULL

Question

Im looking for a best way to select all rows where at least one of these column

job_start, title, visit_hours, name, leave_start and leave_end

has a value, and at least one uniq first_name row must be selected from below table

The result should exclude row 1 and 7

Answer 1

using row_number() to return at least 1 row per first_name , prioritizing those with a non- null column first.

select *
from (
  select t.*
    , row_number() over (
        partition by first_name 
        order by case when job_start is not null
                or title is not null
                or visit_hours is not null
                or name is not null
                or leave_start is not null
                or leave_end is not null
          then 0 
          else 1 
          end
        ) as rn
  from t
) sub
where rn = 1
  or (job_start is not null
    or title is not null
    or visit_hours is not null
    or name is not null
    or leave_start is not null
    or leave_end is not null
  )

Answer 2

In Postgres, you can do this using distinct on :

select distinct on (first_name) t.*
from t
order by first_name,
         (case when job_start is not null or
                    title is not null or
                    visit_hours is not null or
                    name is not null or
                    leave_start is not null or
                    leave_end is not null
               then 0 
               else 1 
          end)