空格和NULL值两码事

<pre name="code" class="sql">PLSQL 里测试:
drop table test1;

create table test1(name varchar2(10));


select * from test1;

insert into test1 values(null);

insert into test1 values('');
--空格
insert into test1 values('   ');
--tab键
insert into test1 values('      ');

select dump(name) from test1 
NULL
NULL
Typ=1 Len=3: 32,32,32
Typ=1 Len=6: 32,32,32,32,32,32

drop table test1;


create table test1(name char(10));




select * from test1;


insert into test1 values(null);


insert into test1 values('');
--空格
insert into test1 values('   ');
--tab键
insert into test1 values('      ');


select dump(name) from test1 
NULL
NULL
Typ=96 Len=10: 32,32,32,32,32,32,32,32,32,32
Typ=96 Len=10: 32,32,32,32,32,32,32,32,32,32
char会空格补足


会自动把TAB键转换为空格