SQL: Nulls are returned when filtering with !=

[matriv]

SELECT POSITION('x',LCASE("first_name")) pos, "first_name" FROM "test_emp" WHERE POSITION('x',LCASE("first_name")) != 0;

Returns:

      pos:i    |  first_name:s
---------------+---------------
4              |Guoxiang       
null           |null           
null           |null           
null           |null           
null           |null           
null           |null           
null           |null           
null           |null           
null           |null           
null           |null           
null           |null           
1              |Xinglin  

but it should be evaluated as null !=0 => null and because it's in the WHERE it should become false

[elasticmachine]

Pinging @elastic/es-search-aggs