Oracle中不等于号问题

在Oracle中，不等于号有以下几种方法：
<>，!=，^=

测试SQL

create table test(
  id int,
  name varchar2(10),
  age int
)

insert into test(id,name,age) values(1,"zhangsan",23);
insert into test(id,name,age) values(2,"lisi","");
insert into test(id,name,age) values(3,"wangwu",null);
insert into test(id,name,age) values(4,"sunqi",27);
insert into test(id,name,age) values(5,"",22);create table