玩一玩 create table A(a char(2),b char(2),c char(3)) insert into a select 'A1', 'B1', 'C1' insert into a select 'A2' , 'B2' , 'C2' insert into a select 'A3', 'B3' , 'C3' select a.a,b.a,c.a from a a,a b,a c where a.a<b.a and b.a<c.a union select a.b,b.b,c.b from a a,a b,a c where a.b<b.b and b.b<c.b union select a.c,b.c,c.c from a a,a b,a c where a.c<b.c and b.c<c.cdrop table a
create table A(a char(2),b char(2),c char(3))
insert into a select 'A1', 'B1', 'C1'
insert into a select 'A2' , 'B2' , 'C2'
insert into a select 'A3', 'B3' , 'C3'
select a.a,b.a,c.a from a a,a b,a c where a.a<b.a and b.a<c.a
union
select a.b,b.b,c.b from a a,a b,a c where a.b<b.b and b.b<c.b
union
select a.c,b.c,c.c from a a,a b,a c where a.c<b.c and b.c<c.cdrop table a