SQL question brushing 584 Looking for user references

Intuitively think of the following sql sentence

# Write your MySQL query statement below
select name from customer where referee_id != 2

But the query result is wrong ,

MySQL Use ternary logic —— TRUE, FALSE and UNKNOWN. Anything to do with NULL Values are compared with the third value UNKNOWN compare .

# Write your MySQL query statement below
select name from customer where referee_id != 2 or referee_id is null