表的左右连接
比如表A
id name
1 A1
2 A2
3 A3
5 A5
表B
id name
1 B1
3 B3
4 B4
6 B6
1.select a.id,a.name,b.id,b.name from A a,B b where a.id=b.id;
交集
id name id name
1 A1 1 B1
3 A3 3 B3
2.select a.id,a.name,b.id,b.name from A a,B b where a.id(+)=b.id;
id name id name
1 A1 1 B1
3 A3 3 B3
4 B4
6 B6
3.select a.id,a.name,b.id,b.name from A a,B b where a.id=b.id(+);
id name id name
1 A1 1 B1
2 A2
3 A3 3 B3
5 A5
比如表A
id name
1 A1
2 A2
3 A3
5 A5
表B
id name
1 B1
3 B3
4 B4
6 B6
1.select a.id,a.name,b.id,b.name from A a,B b where a.id=b.id;
交集
id name id name
1 A1 1 B1
3 A3 3 B3
2.select a.id,a.name,b.id,b.name from A a,B b where a.id(+)=b.id;
id name id name
1 A1 1 B1
3 A3 3 B3
4 B4
6 B6
3.select a.id,a.name,b.id,b.name from A a,B b where a.id=b.id(+);
id name id name
1 A1 1 B1
2 A2
3 A3 3 B3
5 A5
我已经明白了,谢谢你们和所有来讨论的人