1.0
create trigger sc_t
after update of grade on sc
referencign
oldrow as oldtuple
newrow as newtuple
for each row
when(newtuple.grade>=1。0*oldtuple.grade)
insert into sc_u(sno,cno,oldgrade,newgrade)
values(oldtuple。sno,oldtuple.cno,oldtuple.grade,newtuple。grade)
/* 触发器 */
2.0
begin transaction
读取账户甲的金额 belance;
balance=balance—amount;
if(balance<0)then
{打印'金额不足,不能转账’;
rollback;}
else
{读账户乙的余额BALANCE1;
balance1=balance1+amount;
写回 balance1;
commit;}
3。0
create database student;
use student
create table stu
(Sno char(11) Primary key,
Sname char(20) unique,
Ssex char(2),
Sage SMALLINT,
Sdept char(20)
)
create table course
(Cno char(4) PRIMARY KEY,
Cname char(40) NOT NULL,
Cpno CHAR(4),
Ccredit SMALLINT,
FOREIGN KEY(Cpno) references course(Cno)
)
create table sc
(Sno char(11),
Cno char(4),
Grade SMALLINT,
PRIMARY KEY(Sno,Cno),