Question 40: Which of the following queries return 0?

 
(Find all correct answers)
 

a) select count(i)
     from (select 1 as i union select 2 union select null) v1
     where i is null;
 
b) select count(*)
     from (select 1 as i union select 2 union select null) v1
     where i is null;
 
c) select count(*)
     from (select 1 as i union select 2 union select null) v1
     where i <=> null;
 
d) select count(*)
     from (select 1 as i union select 2 union select null) v1
     where i = null;

 
[ SQL Expressions (15%) - NULL Values ]