oracle判断某字段是否为空

1、sql语句中判断非空不能用等号，因为null是特殊字符，必须使用关键字is和not

2、测试数据

a、测试数据

create table atest(
aid varchar2(6),
aname varchar2(50)
)

insert into atest values('1','a');
insert into atest values('2','b');
insert into atest values('3','');
insert into atest values('4','');
insert into atest values('21','');
insert into atest values('22','');
insert into atest values('31','');
insert into atest values('','');

 

 b、判断是否为空

select * from atest where aname is null;

 

 

c、判断不为空

select * from atest where aname is not null;