how to select not null values column dynamically?

I created a table like below. I want to select only NOT NULL column dynamically like(NO, NAME,SAL_1). No need to select SAL,SAL_2.

Note: Initially I don't know the columns values.

create table sample(no integer,name varchar(20),sal integer,sal_1 integer,sal_2 integer);
insert into sample(name,sal_1) values('aaa',10);
insert into sample(no,name,sal_1) values(20,'',20);
insert into sample(sal_1) values(30);

select * from sample;

data like below

NO        NAME    SAL   SAL_1 SAL_2
20       (null)   (null)  20  (null)
(null)    (null)  (null)  30  (null)
(null)    aaa     (null)  10  (null)

Expected op:

NO       NAME   SAL_1
20      (null)  20
(null)  (null)  30
(null)  aaa     10