Sq lServer触发器的使用

创建表：

CREATE TABLE [dbo].[GeneralRule](
    [ID] [int] NOT NULL,
    [GeneralRuleName] [nvarchar](50) NULL,
    [DeleteFlag] [int] NOT NULL
)

CREATE TABLE [dbo].[DetailRule](
    [ID] [int] NOT NULL,
    [DetailRuleName] [nvarchar](50) NULL,
    [ParentId] [int] NULL,
    [DeleteFlag] [int] NOT NULL,
)

CREATE TABLE [dbo].[DetailRule_bak](
    [ID] [int] NOT NULL,
    [DetailRuleName] [nvarchar](50) NULL,
    [ParentId] [int] NULL,
    [DeleteFlag] [int] NOT NULL,
)

创建触发器：

--增加
create trigger  triAddGeneralRule
   on DetailRule
for insert --为什么事件触发
    as
begin
    insert into [DetailRule_bak](ID,detailRuleName,ParentId,DeleteFlag)
    select ID,detailRuleName,ParentId,DeleteFlag
    from INSERTED
end

--删除
create trigger  triDelGeneralRule
   on GeneralRule
for delete --为什么事件触发
    as
delete DetailRule
from DetailRule dr,Deleted d
where dr.parentId=d.ID

--修改
create trigger  triGeneralRule
   on GeneralRule
for update --为什么事件触发
    as
if update (ID)
begin
    update DetailRule
    set parentId=i.ID
    from DetailRule dr,Deleted d,Inserted i --2个临时表Deleted和Inserted,分别表示触发事件的旧与新记录
    where dr.parentId=d.ID
end

if else 触发器

create table employee(emp_id int,emp_name nvarchar(50),gender int,department int,salary numeric(10,2))

create table updated(emp_id int,salary numeric(10,2))

insert into employee values(1,'tom',10,10,6000.00)

insert into updated values(1,6500.00)

create trigger up_salary on employee INSTEAD OF update
    as if update (salary)
    begin
        declare @newSalary numeric(10,2)
        declare @oldSalary numeric(10,2)
        select  @newSalary = salary from updated
        select @oldSalary = salary from employee where emp_id = (select emp_id from updated)
        if @newSalary > @oldSalary * 1.1
            print '工资变动不能超过原来工资的10%'
        else
            update employee set salary = @newSalary where emp_id = (select emp_id from updated)
    end
go