MSQL数据库多表查询有关问题

select a.role_id,a.auy_id,a.auy_name,m.md_name from role_auy as ra left join auy as a on a.auy_id=ra.auy_id inner left join module as m on m.md_id=a.md_id where ra.role_id=1;

------解决方案--------------------


SQL code

SELECT * FROM role_auy AS ra LEFT JOIN auy AS a ON ra.auy_id = a.auy_id LEFT JOIN module AS m ON a.md_id = m.md_id WHERE ra.role_id = '角色ID'

如果还要关联用户表 就在 WHERE前面加 LEFT JOIN sub AS s ON ra.role_id = s.role_id

------解决方案--------------------

功能放在相应的模块下面，表示模块id 是已知且固定的
又角色id已知
则连接应使用内连接或逗号连接，因为是要取得存在的功能

SQL code
select* from role_auy, auy
 where role_auy.auy_id=auy.auy_id
  and role_auy.role_id=角色id
  and auy.md_id=模块id