java网吧计费系统

create database netbar create table card ( id varchar(10) primary key not null, password varchar(50), balance int , username varchar(50) ) create table computer ( id varchar(10) primary key not null, onuse char(1) not null, notes varchar(100) ) create table record ( id int identity(1,1) not null, cardid varchar(10) foreign key references card(id), computerid varchar(10) foreign key references computer(id), begintime varchar(20), endtime varchar(20), fee numeric ) select * from computer insert into computer values('1','0','第一排1号') insert into computer values('2','0','第一排2号') insert into computer values('3','0','第一排3号') insert into computer values('4','0','第一排4号') insert into computer values('5','0','第一排5号') insert into computer values('6','0','第一排6号') insert into computer values('7','0','第一排7号') insert into computer values('8','0','第一排8号') insert into computer values('9','0','') select * from card insert into card values('1','111',10,'孙悟空') insert into card values('2','222',21,'猪八戒') insert into card values('3','333',23,'沙和尚') insert into card values('4','444',56,'白晶晶') insert into card values('5','555',76,'紫霞仙子') insert into card values('6','666',88,'牛魔王') insert into card values('7','777',54,'白骨精') select * from record update card set balance=0 where id=1