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实验过程：
一、在student数据库上练习创建并调用课堂讲授的存储过程和触发器。
1.创建一个instead of触发器，要求实现一下功能：在t_student表上创建一个删除类型的触发器notallowdelete,当上除记录时，显示不允许删除的提示信息 use students go
if exists(select name from sysobjects
where name=‘notallowdelete‘ and type=‘tr‘) drop trigger notallowdelete go
CREATE trigger notallowdelete
if(@@error<>0)---------- @@代表系统变量 set @[email protected]@error return @errorvalue end
执行该存储过程:
declare @nl as int, @num as char(10), @returnvalue as int set @num=‘S99002‘
exec stu_age @num,@nl output
print ‘学号为‘+rtrim(cast(@num as char(10)))+‘的学生的年龄是‘+cast(@nl as
char(2))+‘岁‘ 执行结果：
3.创建一个名为stu_info的存储过程，要求:输入学号，查询学生所在的班级、学
生姓名，课程名和选课成绩。
CREATE proc stu_info @xh as char(10) as begin
select substring(s_number,4,1) as ‘班级‘,s_name as ‘姓名‘,c_name as ‘课程名‘,score as ‘
成绩‘
from t_student inner join t_score
on s_number=s_num inner join course on c_number=c_num where @xh=s_number end GO
执行该存储过程： exec stu_info‘S99001‘
4.求一个数的阶乘（没有返回值） CREATE proc jiecheng @i as int as
declare @result as int declare @ii as int set @result=1 set @[email protected] while @i>1 begin
set @[email protected]*@i
set @[email protected] if @i>1 continue else begin print @ii
print rtrim(cast(@ii as char(2)))+‘的阶乘为：‘------该输出必须使用转换数据类型
的函数cast,否则就会出现如下错误：
print @result end end GO
执行该存储过程： declare @data as int set @data=5
exec jiecheng @data 执行结果： 5
5的阶乘为： 120
5.求一个数的阶乘，一个输入，一个输出。(带有输出参数的) CREATE proc jiecheng
@i as int,@result as int output as
declare @ii as int set @result=1 set @[email protected] while @i>0 begin
set @[email protected]*@i set @[email protected] if @i>1 continue else break end GO
执行该存储过程:
declare @data as int,@sum as int set @data=5
exec jiecheng @data,@sum output
print rtrim(cast(@data as char(2)))+‘的阶乘为:‘ print @sum
执行结果为： 5的阶乘为: 120
(6)带有默认值的存储过程。
输入学号，查询学生所在的班级、学生姓名，课程名和选课成绩。（stu_info1） CREATE proc stu_info1 @num as char(10)=‘S99001‘ as
select substring(s_number,4,1) as ‘班级‘, s_name as ‘姓名‘, c_name as ‘课程名‘, score as ‘成绩‘
from t_student inner join t_score
on s_number=s_num inner join course on c_number=c_num where @num=s_number GO
执行存储过程: exec stu_info1 执行结果：
当不输入指定的学号时，数据库自动给@num赋值为：S99001
三、在BBS数据库上设计所需触发器
? 发表主帖，用户积分加10分，版块发帖量加1。
CREATE trigger publish on BBSTopic for insert as
begin
declare @yhID as int
declare @bkID as int
select @yhID=TUID , @bkID=TSID from inserted update BBSUser set UPoint=UPoint+10 where @yhID=UID update BBSSession
set STopicCount=STopicCount+1
where @bkID=SID end
执行插入语句后：
Insert
IntoBBSTopic(TID,TSID,TUID,TTopic,TContents,TClickCount,TFlag,TLastClickT,TReplyCount)
values(‘6‘,‘2‘,‘1‘,‘买卖商场 ‘)
执行该操作后，BBSUser表中的UID=1的用户‘火云邪神’的积分UPoint加10；BBSSseeion表中的SClickCount加1。
跟帖，用户积分加1，主帖的回复数量加1、更新最后回复
时间，版块发帖量加1。
create trigger gt on BBSReply
for insert,update as begin
declare @yhID as int,@ztID as int,@bkID as int
select @yhID=RUID,@ztID=RTID,@bkID=RSID from inserted update BBSUser set UPoint=UPoint+1 where @yhID=UID update BBSTopic
set TReplyCount=TReplyCount+1 where @ztID=TID
update BBSSession
set STopicCount=STopicCount+1 where @bkID=SID end
执行插入语句： insert into
BBSReply(RID,RTID,RSID,RUID,RTopic,RContents) values(‘6‘,‘2‘,‘1‘,‘2‘,‘就业难‘,‘机会不平等‘)
在BBSUser表中2号用户的UPoint就会加1;在BBSTopic表中2号主帖的回复量（TReplyCount）就会变为7；在BBSSession表中版块发帖量（STopicCount）就会变为1601.
? 删除跟帖，用户积分减20分，版块发帖量减1。
create trigger scgt on BBSReply for delete,update as begin
declare @yhID as int,@bkID as int
select @yhID=RUID ,@bkID=RSID from deleted update BBSUser set UPoint=UPoint-20 where @yhID=UID
update BBSSession
set STopicCount=STopicCount-1 where @bkID=SID end
删除主帖，用户积分减50分，版块发帖量减1，删除所有跟帖。
create trigger sczt on BBSTopic for delete,update as begin
declare @yhID as int declare @bkID as int
declare @gtID as int
select @yhID=TUID,@bkID=TSID from deleted update BBSUser set UPoint=UPoint-50 where @yhID=UID
update BBSSession
set STopicCount=STopicCount-1 delete
from BBSReply
where RTID=(select TID from deleted )