mysql中not exists的简单理解

http://www.cnblogs.com/glory-jzx/archive/2012/07/19/2599215.html

http://sunxiaqw.blog.163.com/blog/static/990654382013430105130443/

这篇文章写的很清楚了，请参考,多谢原作者。

select loan_user_id from sp_invest_project p where exists(
                         select 1 from temp_stock_enterprise e where e.user_id = p.loan_user_id 
                         ) ;
                         
select loan_user_id from sp_invest_project p where  loan_user_id in (
                         select user_id  from temp_stock_enterprise
                         ) ;

上述两种写法应该是一致的。