test1:
a b
1 101
2 102
test2:
a c
1 1001
3 1003
1.内连接
SQL> select * from test1 inner join test2 on test1.a = test2.a;
A B A C
---------- ---------- ---------- ----------
1 101 1 1001
2.左外连接
SQL> select * from test1 left outer join test2 on test1.a = test2.a;
A B A C
---------- ---------- ---------- ----------
1 101 1 1001
2 102
3.又外连接
SQL> select * from test1 right outer join test2 on test1.a = test2.a;
A B A C
---------- ---------- ---------- ----------
1 101 1 1001
3 1003
4.全外连接
SQL> select * from test1 full outer join test2 on test1.a = test2.a;
A B A C
---------- ---------- ---------- ----------
1 101 1 1001
3 1003
2 102
5.交叉连接
SQL> select * from test1, test2;
A B A C
---------- ---------- ---------- ----------
1 101 1 1001
1 101 3 1003
2 102 1 1001
2 102 3 1003
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