left outer join Right Outer Join --------------------------------------------------------------- 把下面的语句运行一把就知道了 drop table test_a go drop table test_b go create table test_a (a int, b int) go create table test_b (a int, b int) go insert test_a values (1,1) insert test_a values (2,1) insert test_a values (3,1) go insert test_b values (4,1) insert test_b values (2,1) insert test_b values (3,1) go select test_a.* ,test_b.* from test_a left join test_b on test_a.a=test_b.a
select test_a.* ,test_b.* from test_a right join test_b on test_a.a=test_b.a
select test_a.* ,test_b.* from test_a inner join test_b on test_a.a=test_b.a
select test_a.* ,test_b.* from test_a full join test_b on test_a.a=test_b.a
