Android SQLite data Aceess of a null value attribute

I am working on my android project with SQLite database. I need to get all the information of the perons who doesn't have a phone. I tried with following thre开发者_StackOverflow社区e ways but didn't provide the required data. I have assign phone varchar(64), when create table.

select * from person where phone='null'
select * from person where phone=null
select * from person where phone=''

can anyone tell why is this happening and how can I get the information. Thanks

To query a null value use this sql statement:

select * from person where phone IS null