PostgreSQL 表之间连接测试

SQL表操作与联接示例

最新推荐文章于 2024-05-30 10:14:49 发布

cejutue

最新推荐文章于 2024-05-30 10:14:49 发布

阅读量669

点赞数

CC 4.0 BY-SA版权

分类专栏： C++札记数据库文章标签： SQL

本文链接：https://blog.youkuaiyun.com/chijingjing/article/details/96480805

C++札记同时被 2 个专栏收录

89 篇文章

订阅专栏

数据库

23 篇文章

订阅专栏

本文通过创建两个临时表atmp和atmp2，并插入数据，演示了如何使用不同的SQL联接类型来合并这两个表的数据。包括自然联接、内联接、左联接、全联接和右联接等，展示了各种联接方式的特点及应用场景。

create table if not EXISTS atmp(oid int8 PRIMARY key);
INSERT into atmp values(1) on conflict(oid) do update set OID = 1;
INSERT into atmp values(2) on conflict(oid) do update set OID = 2;
INSERT into atmp values(3) on conflict(oid) do update set OID = 3;
INSERT into atmp values(1) on conflict(oid) do update set OID = 1;

create table if not EXISTS atmp2(oid int8 PRIMARY key);
INSERT into atmp2 values(1) on conflict(oid) do update set OID = 1;
INSERT into atmp2 values(4) on conflict(oid) do update set OID = 4;
create table if not EXISTS atmpret(oid int8 PRIMARY key);

select  * from atmp natural join atmp2;
select  * from atmp as a inner join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a left join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a full join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a right join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a  join atmp2 as b  on a.oid = b.oid ;