Resolved: Exclude null value from comparison across columns

id   col1    col2    col3    col4
1    A       A       C
2            B       B       B
3    D               D

id   col1    col2    col3    col4   is_a_match
1    A       A       C              FALSE
2            B       B       B      TRUE
3    D               D              TRUE

select *,
     case  
         when col1 = col2
                and col2 = col3
                and col3 = col4
         then 'TRUE'
         else 'FALSE'
     end as is_a_match
from my_table

select t.*,
       (select count(distinct x.col)
        from (
          values (t.col1), 
                 (t.col2), 
                 (t.col3), 
                 (t.col4)
        ) as x(col)
        where x.col is not null) = 1 as is_a_match
from the_table t

select t.*, 
       (select count(distinct x.val)
        from jsonb_each_text(to_jsonb(t) - 'id') as x(col, val)
        where x.val is not null) = 1
from the_table t