存储过程、触发器、数据完整性

By TreeDream

存储过程、触发器、数据完整性存储过程创建存储过程修改存储过程删除存储过程触发器创建触发器数据完整性约束默认值创建默认值绑定默认值解除默认规则创建规则绑定和解除规则,删除

存储过程

将需要多次调用以实现某个特定任务的代码段编成一个过程

创建存储过程

create procedure exp1
as
select *
from Stock
Go
?
exec exp1

带参数的存储过程

if exists (select name from sysobjects where name =‘exp2‘ and type = ‘P‘)
drop procedure exp2
Go
create procedure exp2 @mno char(8),@mname varchar(50),@mspeci varchar(20)
as
insert into Stock(mat_num,mat_name,speci)
values(@mno,@mname,@mspeci)
GO
?
execute exp2 ‘m030‘,‘护套绝缘电线‘,‘BVV-35‘

带默认输入参数的存储过程

if exists (select name from sysobjects where name = ‘exp3‘ and type = ‘P‘)
drop procedure exp3
GO
create procedure exp3 @mname varchar(50) = ‘%绝缘%‘,@pno char(8) = ‘20110005‘
as
select mat_name,speci,prj_name,prj_status
from Stock,Salvaging,Out_stock
where Stock.mat_num = Out_stock.mat_num and Salvaging.prj_num = Out_stock.prj_num and mat_name like @mname and Salvaging.prj_num = @pno
GO
?
execute exp3
execute exp3 @pno = ‘20110002‘

带输出参数的存储过程

if exists (select name from sysobjects where name = ‘exp4‘ and type = ‘P‘)
drop procedure exp4
GO
create procedure exp4 @pn char(8),@sum int output
as
select @sum = sum(amount)
from Out_stock
where prj_num = @pn
GO
?
declare @total int
execute exp4 ‘20110002‘,@total output
print ‘总量‘+ cast(@total as varchar(20))

修改存储过程

修改和创建相同alter

删除存储过程

drop procedure exp4

触发器

当用户进行插入，删除，更新等数据操作的时候，自动触发所定义的SQL语句

创建触发器

insert触发器，同时将数据复制到基本表和内存中的Inserted表中

if exists (select name from sysobjects where name = ‘tr1_stock‘ and type = ‘P‘)
drop trigger tr1_stock
GO
create trigger tr1_stock
on Stock
after insert
as
declare @amount int
select @amount = amount
from inserted
if @amount < 1
Begin
rollback tran
raiserror (‘amount must be greater than 1!‘,16,10)
END
GO

create trigger tr1_outstock
on Out_stock
after insert
as
Begin
declare @m_num char(8),@m_amount int
select @m_num = mat_num,@m_amount = amount
from inserted
update stock
set amount = amount - @m_amount
where mat_num = @m_num
END
GO

delete触发器：将删除的数据保存于deleted中，SQL语句中还可以引用

create trigger tr2_stock
on Stock
after delete
as
Begin
declare @mat_num char(8)
select @mat_num = mat_num
from deleted

delete
from Out_stock
where mat_num = @mat_num
END

update触发器：合并了inserted deleted 触发器

create trigger tr3_stock
on Stock
after update
as
declare @amount_new int,@amount_old int,@mat_num char(10)
select @amount_new = amount,@mat_num = mat_num
from inserted
if @amount_new < 1
Begin
select @amount_old = amount
from deleted
update Stock
set amount = @amount_old
where mat_num = @mat_num
END

数据完整性

约束

• 建表的时候：列级完整性约束，表级完整性约束

• alter table Salvaging
  add constraint PK_salvaging primary key(prj_num)
  ?
  alter table Salvaging
  add constraint data_check check(start_date<=end_date)
  ?
  alter table Salvaging
  add constraint DF_salvaging default (0) for prj_status
  ?
  alter table Salvaging
  drop constraint data_check

默认值

默认值对象独立于表

创建默认值

create default _Getdate
as getdate()

绑定默认值

sp_bindefault _Getdate, ‘Out_stock.get_date‘

解除默认

sp_unbindefault _Getdate

规则

check约束是在create table中建立的，规则独立于表

创建规则

create rule amount_rule
as
@amount>0 and @amount<=100

绑定和解除规则,删除

create rule amount_rule
as
@amount>0 and @amount<=100
?
sp_bindrule amount_rule,‘Stock.amount‘
sp_unbindrule amount_rule,‘Stock.amount‘
?
drop rule amount_rule