select A.a, A.b, A.c, B.d from A, B where A.a=B.a union select A.a, A.b, A.c, NULL from A, B where A.a<>B.a;
select A.a, A.b, A.c, B.d x from A, B where A.a=B.a(+);如: create table dali.test1(a int,b int); create table dali.test2(a int,b int);insert into dali.test1 values(1,456); insert into dali.test1 values(2,427); insert into dali.test2 values(1,45456); insert into dali.test2 values(3,45656);---内连接 select * from dali.test1 a, dali.test2 b where a.a=b.a;---左连接 select * from dali.test1 a, dali.test2 b where a.a=b.a(+);---右连接 select * from dali.test1 a, dali.test2 b where a.a(+)=b.a;---完全连接 select * from dali.test1 a, dali.test2 b where a.a=b.a(+) union select * from dali.test1 a, dali.test2 b where a.a(+)=b.a;---迪卡尔 select * from dali.test1, dali.test2;
union
select A.a, A.b, A.c, NULL from A, B where A.a<>B.a;
create table dali.test1(a int,b int);
create table dali.test2(a int,b int);insert into dali.test1 values(1,456);
insert into dali.test1 values(2,427);
insert into dali.test2 values(1,45456);
insert into dali.test2 values(3,45656);---内连接
select * from dali.test1 a, dali.test2 b where a.a=b.a;---左连接
select * from dali.test1 a, dali.test2 b where a.a=b.a(+);---右连接
select * from dali.test1 a, dali.test2 b where a.a(+)=b.a;---完全连接
select * from dali.test1 a, dali.test2 b where a.a=b.a(+)
union
select * from dali.test1 a, dali.test2 b where a.a(+)=b.a;---迪卡尔
select * from dali.test1, dali.test2;