select *  from company

select c.code from company c;

select m.bookname from myview m; (myview为视图)

select mybook.bookname,mybook.bookType from mybook;

select c.name from company c where c.name like '%a%'; 

select c.name from company c order by c.code ;

select c.name from company c order by c.code desc;

insert into company(code ,name) values('','Amazon');

insert into company values('','twitter');

delete from company where code='';

update company set name='华为' where code='';

select count(company.name) as totalcount from company

select sum(company.code) as total from company

select avg(company.code) as avgCode from company

select max(company.code) as maxCode from company

select min(company.code) as minCode from company

select b.companyNo, b.id ,group_concat(b.bookName) from mybook b group by b.companyNo；

select b.companyNo, b.id ,group_concat(b.bookName) from mybook b group by b.companyNo with rollup;

select b.companyNo, b.id ,group_concat(b.bookName) from mybook b group by b.companyNo having b.companyNo >=''