有4个表,ISSUES(用户提交的issue基本信息) , MESSAGES(issue相关的消息) , DOCUMENTS(issue相关的附件), COMMENTS(用户和客服之间的电子邮件交流记录)。每个issue有0~n个messages, 0~n个documents,0~n个comments每个表中都有issue_ID字段,在ISSUE_DB_ISSUE中是主键,在其它三个表中是外键。我要:在一个页面内显示所有的ISSUE,如果该ISSUE有documents, comments或者message也都显示出来。不考虑效率。非常感谢!100分献上。
from issues t1,
messages t2,
documents t3,
comments t4
where t1.issue_id = t2.issue_id(+)
and t1.issue_id = t3.issue_id(+)
and t1.issue_id = t4.issue_id(+)
order by t1.issue_id;
up改成left join的方式select t1.* from issues left join messages t2 on t1.issue_id = t2.issue_id left join on documents t3 on t1.issue_id = t3.issue_id left join on comments t4 on t1.issue_id = t4.issue_id和(+)是一样的方式,不过是用标准的left join实现的。
issues t1,
messages t2,
documents t3,
comments t4
where t1.issue_id= t2.issue_id(+)
and t1.issue_id= t3.issue_id(+)
and t1.issue_id= t4.issue_id(+)
orderby t1.issue_id;