oracle 外连接

最新推荐文章于 2025-12-05 12:37:18 发布

最新推荐文章于 2025-12-05 12:37:18 发布 · 79 阅读

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#数据库

本文深入探讨了Oracle中左外连接、右外连接和全连接的概念，并通过具体实例展示了如何使用这些连接类型来整合数据。包括从创建虚拟表到进行连接操作的详细步骤。

//oracle 外连接 //from table_name1 {left | right | full} outer join table_name2 //using (common_column) //table_name1,table_name2是两个连接的表 //left:左外连接 //right:右外连接 //full:全连接,左外连接和右外连接的并集 //下面是一个实例： with ta as( select 101 wlbh,4 cssl from dual union all select 301,5 from dual union all select 501,6 from dual union all select 102,0 from dual union all select 201,0 from dual) ,tb as( select 101 wlbh,2 rksl from dual union all select 102,4 from dual union all select 301,5 from dual union all select 101,1 from dual) ,tc as( select 101 wlbh,3 cksl from dual union all select 102,1 from dual union all select 201,5 from dual union all select 101,2 from dual) select * from (select wlbh,nvl(cssl,0) cssl,nvl(rksl,0) rksl,nvl(cksl,0) cksl from (select wlbh,sum(cssl) cssl from ta group by wlbh) full outer join (select wlbh,sum(rksl) rksl from tb group by wlbh) using (wlbh) full outer join (select wlbh,sum(cksl) cksl from tc group by wlbh) using (wlbh)) order by wlbh / WLBH CSSL RKSL CKSL ---------- ---------- ---------- ---------- 101 4 3 5 102 0 4 1 201 0 0 5 301 5 5 0 501 6 0 0

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