大型数据库复习

1.创建数据库

create database 教师管理
create table Teachers(
TID varchar(50) not null,
TName varchar(50) null,
TGender varchar(50) null,
TTitle varchar(50) null,
TSalary int null,
TDeptID varchar(50) null,
primary key(TID)
)
create table Departments(
DeptID varchar(50) not null,
DeptName varchar(50) null,
DeptSuperID varchar(50) null,
PRIMARY KEY(DeptID)
)

2.插入记录

INSERT INTO DEPARTMENTS VALUES ('1','Computer','J001')
INSERT INTO DEPARTMENTS VALUES ('2','English','W001')
INSERT INTO DEPARTMENTS VALUES ('3','Economy','JG001')

INSERT INTO TEACHERS VALUES('J001','张林','男','教授',5500,'1')
INSERT INTO TEACHERS VALUES('J002','赵强','男','副教授',5000,'1')
INSERT INTO TEACHERS VALUES('J003','陈伟','男','教授',5600,'1')
INSERT INTO TEACHERS VALUES('J004','张婷婷','女','讲师',4000,'1')
INSERT INTO TEACHERS VALUES('JG001','吕楠','女','教授',5200,'3')
INSERT INTO TEACHERS VALUES('JG002','孙新林','男','讲师',3800,'3')
INSERT INTO TEACHERS VALUES('W001','卓华','男','教授',5800,'2')
INSERT INTO TEACHERS VALUES('W002','谢世杰','男','讲师',3800,'2')
INSERT INTO TEACHERS VALUES('W003','陈芳','女','助教',3000,'2')

3.数据库操作、事务

select *from Teachers 
select *from Departments 
//添加外键
alter table Departments add constraint con_1 foreign key(deptsuperid) references Teachers(TID)
alter table Teachers add constraint con_2 foreign key(TDeptID) references Departments(DeptID)

select *from Teachers 
select *from Departments 
//显式事务 try…catch回滚
go
begin try
begin transaction 
insert into teachers values('2015','蛊','男',null,null,null)
insert into departments values('4','Petroleum','123456')
commit tran
end try
begin catch
rollback transaction
end catch
select *from Teachers 
select *from Departments 
go

//显式事务@@error回滚
go
declare @del_error int,@ins_error int
begin transaction
insert into Teachers(tid,tname,tgender) values ('2015','更好','男')
select @del_error =@@ERROR 
insert into Departments (DeptID ,DeptName ,DeptSuperID )values('4','Petroleum','123456')
select @ins_error  =@@ERROR
if @del_error =1 and  @ins_error =1
begin
commit tran
end
else
begin
rollback tran
end
go
select *from Departments
//删除主键和约束
alter table departments drop constraint con_1
alter table teachers drop constraint PK__Teachers__C456D7297F60ED59
alter table teachers drop constraint con_2
alter table departments drop constraint PK__Departme__0148818E03317E3D

4.索引、视图、触发器等

go
create unique clustered index ix_TID on teachers(TID)
with (fillfactor=70)
go
sp_helpindex 'teachers'
//创建视图 instead of触发器
go
create view Teachers_Dept5
as
select tid,Tname,Tdeptid,deptname from Teachers,Departments
go

create trigger t5 on Teachers_Dept
instead of insert
as
declare @tid1 varchar(50),@Tname1 varchar(50),@Tdeptid1 varchar(50),@deptname1 varchar(50)
select @tid1=tid,@Tname1=Tname,@Tdeptid1=Tdeptid,@deptname1=deptname
from inserted

insert Teachers(tid,tname,Tdeptid)values('P001','李华斌','5')
insert departments(deptid,deptname)values('5','Production')

select * from Teachers_Dept
select * from departments

//添加列，游标计算
alter table departments add DeptCount int null
declare @sum int,@Tdeptid varchar(30)
declare num cursor 
for select Tdeptid from Teachers join Departments
 on TDeptID=DeptID 
open num
fetch next from num into @Tdeptid
while(@@FETCH_STATUS=0)
begin
  
  select @sum=COUNT(*) from Teachers join Departments
  on TDeptID=DeptID 
  where TDeptID=@Tdeptid
  update Departments
  set DeptCount=@sum
  where current of num
  fetch next from num into @Tdeptid
end
close num
deallocate num 
select * from Departments

5.DBCC分析方法

dbcc traceon(3604)
dbcc extentinfo(教师管理,departments)
dbcc page(教师管理,1,21,1)
30000800 04000000 04000003 0014001c
00200031 436f6d70 75746572 4a303031
30:状态位，表示变长
0800：表示找到字段数的位置
04000000：代表第四个字段的值为4
0400：表示字段数
03：null位图
1400，1c00：表示第2变长个字段，第3个变长字段结束位置
436f6d70 75746572 4a30：代表computer 30为随机数
4a303031：表示字段三数据

6.自定义函数方法、存储过程、触发器等

go
create function demo7(@name varchar(30))
returns int
as
begin
   declare @sum int
   select @sum=count(*) from Teachers join  Departments 
   on TDeptID=DeptID where DeptName=@name and TGender='女'
   return (@sum)
end
go
print dbo.demo7('Computer')
//存储过程
go
create proc num1(@deptid varchar(30),@aversal int output)
as
begin
  if not exists(select * from  Departments where DeptName=@deptid)
   print '该部门不存在'
  else
    select AVG(TSalary) from Teachers join  Departments on TDeptID=DeptID where DeptName=@deptid
end 
declare @sal int
exec num1 'English',@sal output
print @sal
go
//insert触发器等等
go
create trigger t_name on Teachers
for insert(update,delete) 
as
declare @avgsalary int
	select @avgsalary = AVG(TSalary) from Teachers t join Departments d on t.TDeptID=d.DeptID group by d.DeptName
update Departments
	set DeptAvgSalary = @avgsalary
select DeptAvgSalary from Departments where DeptName = 'Computer'
insert into Teachers (TID,TName,Tsalary) values('10086','张老师',5000)
select DeptAvgSalary from Departments where DeptName = 'Computer'
go