sql问题

[qqyatou]

说明下，上面A表的数据是从B表里来的，现在想从B表里查出A表里没有的数据，我写了个sql 但是效率非常低，数据多的时候就死翘翘了，
想请教下 还有什么好的方法没有，
先谢谢了

create table A(
a varchar(50),
b varchar(50),
c varchar(50),
d varchar(50),
e varchar(50),
f varchar(100)

)
insert into A(a,b,c,d,e,f) values('1','1','3','4','aaaa','111111');
insert into A(a,b,c,d,e,f) values('3','2','6','7','bbbb','222222');
insert into A(a,b,c,d,e,f) values('6','4','7','3','cccc','333333');


create table B(
a varchar(50),
b varchar(50),
c varchar(50),
d varchar(50),
e varchar(50)
)
insert into B(a,b,c,d,e) values('1','1','3','4','aaaa');
insert into B(a,b,c,d,e) values('3','2','6','7','bbbb');
insert into B(a,b,c,d,e) values('6','4','7','3','cccc');
insert into B(a,b,c,d,e) values('3','5','2','1','dddd');
insert into B(a,b,c,d,e) values('4','5','3','1','eeee');
insert into B(a,b,c,d,e) values('6','5','5','5','fffff');
insert into B(a,b,c,d,e) values('7','6','2','8','rrrrr');

select * from A

select * from B

select * from B 
where
   a not in (select a from A)
or b not in (select b from A)
or c not in (select c from A)
or d not in (select d from A)


drop table A
drop table B

[-晴天]

select * from b
where not exists(select 1 from a where a=b.a or b=b.b or c=b.c or d=b.d)

[王向飞]

select a,b,c,d,e from B
except
select a,b,c,d,e from A

[fpzgm]

select * from B 
where not exists
(select 1 from A where A.a=B.a and A.b=B.b and A.c=B.c and A.d=B.d and A.e=B.e)

[luoyefeng1022]

各显神通！2楼好！学习了！