sql联合查询语句

'找到有用户名和证书的应用的app_id

select c.app_id from t_app_certpolicy_link c intersect select b.app_id from t_app_pwdpolicy_link

'查找应用下的账号，用户状态为使用中

select b.account_id ,b.username from t_account b inner join t_user a on a.userstate='0'and a.user_id=b.user_id inner join t_app_account_link c  on c.app_id='2c908d55363d402901363d456ef400df' and b.account_id =c.account_id order by username