select*from user where city='北京' order by credit asc; select*from user where sex='男' order by personId asc; select*from user where ename!='null' order by ename asc; select city,count(userId) from user group by city; select sex,avg(credit) from user group by sex; select*from user where name!='null' order by credit desc limit 3; select*from user where sex='男' order by credit asc limit 3; select city,avg(credit)>350 from user group by city