mysql as, order by,where/sum,avg,min,max
create table student ( user_id varchar(50) not null, user_name char(50) not null, age tinyint default '0', gender enum('M','F'), year enum('1','2','3'), hakjum char(1)); hakjum 컬럼 삭제 alter table student drop hakjum; 다음 데이터 입력 user_id user_name age gender year a1 Tom 15 M 2 a2 Jane 16 F 3 a3 Yakima 14 M 1 a4 Yong 14 Null 1 a5 Minyo 0 F Null a6 Kang 15 Null 2 a7 Kim 0 M Null a8 Miranda 15 F 2 inse..
2015. 8. 5.