这是用左连接的写法 select t_thread.id, t_thread.content, t_author.id, t_author.name from thread t_thread left join author t_author on t_thread.author_id=t_author.id
没有必要使用左连接啊,你这个只是关联查询 ,1 楼的就可以了select T.id, T.content, A.id, A.name from thread T, author A where T.author_id = A.id
select t_thread.id, t_thread.content, t_author.id, t_author.name from thread t_thread, author t_author where t_thread.author_id=t_author.id。
select t_thread.id, t_thread.content, t_author.id, t_author.name from thread t_thread left join author t_author on t_thread.author_id=t_author.id