sqlserver数据库触发器和存储过程案例学习

 

--创建表
create table zhuangzhan
(
name nvarchar(10),
code varchar(20)
);
--往表添加一列
alter table zhuangzhan add descition int;
--添加数据
select * from  zhuangzhan
insert zhuangzhan values('王五','',10000);
insert zhuangzhan values('李四','',0);

--给表创建触发器用于添加数据出发,不允许添加code相同的数据
alter trigger mytrigger on zhuangzhan
for insert
as
begin  tran
 if exists(select code from zhuangzhan group by code having count(code)=2)
      begin
      rollback   tran
      end
  else
      begin
      commit   tran
      end
end
--测试
insert zhuangzhan values('王五','',1);
--移除存储过程
drop procedure oneTOother_proc
--创建存储过程
create proc myproc
(
--输入参数
@names nvarchar(20),
@code varchar(20),
@i int output --输出参数
)
as
declare @counts int
begin tran
select @counts=count(code) from zhuangzhan where code=@code
if @counts>=1
    begin
    set @i=1
    rollback tran
    end
else
    begin
    insert into zhuangzhan values(@names,@code,1)
    commit tran
    set @i=0
    end
go
select * from zhuangzhan
declare @i int
exec myproc'EXO','',@i output print @i
--模拟银行转账,实现事物的用法
create proc oneTOother_proc
(
--输入参数
@outMoney int,--转帐金额
@formPeople varchar(20),--汇款人
@toPeopleCode varchar(20)--收款人账号
)
as
declare @yuE int --汇款人余额
declare @i int
declare @tocode int
declare @error int --定义错误号记录
select @yuE=descition from zhuangzhan where name=@formPeople
select @i=COUNT(name) from zhuangzhan where name=@formPeople
    if(@yuE<@outMoney)
    begin
        print @formPeople+'账户余额不足'
        return
    end
    else if(@i=0)
        begin
        print '汇款人'+@formPeople+'不存在'
        return
        end
    else

    select @tocode=count(code) from zhuangzhan where code=@toPeopleCode
    if(@tocode<1)
        begin
            print '收款人账号'+@toPeopleCode+'不存在'
            return
        end
        else
            begin tran --开始事物
            begin
            update zhuangzhan set descition=descition-@outMoney where name=@formPeople
            set @error=@error+ @@ERROR
            update zhuangzhan set descition=descition+@outMoney where code=@toPeopleCode
            set @error=@error+ @@ERROR
            end
        if(@error>0)
        begin
            rollback  transaction
        end
        else
        begin
            commit tran
            print @error
            print @formPeople+'给账号为:'+@toPeopleCode+'汇款'+cast(@outMoney as varchar(10))+'元'
        end
go

select * from zhuangzhan

exec oneTOother_proc 500000,'王五',''