SqlServer存储过程,学习

存储过程：存储过程（Stored Procedure）是在大型数据库系统中，一组为了完成特定功能的SQL 语句集，经编译后存储在数据库中，用户通过指定存储过程的名字并给出参数（如果该存储过程带有参数）来执行它。功能强大，限制少

如何调用存储过程

 --无参数的存储过程
 exec sp_databases;

 --有参数的
 exec sp_helpdb TestDataBase;

 exec sp_renamedb TestDataBase, TDB;
 -- 当参数较多的时候，建议使用显示赋值
 exec sp_renamedb @newname='Testdatabase', @dbname='TDB';

创建,修改无参存储过程:

创建:

-- 一个无参的查询存储过程
/*
create proc usp_存储过程名
as
    查询步骤
*/
go
create proc usp_spFenYe
as
    select * from dbo.fn_fenye(1,10);--一个分页的fn,获取第一页的数据,10条/页
go

修改已有的存储过程usp_Test,以实现转账为例子(开启事务),

 alter proc usp_Test
 as
 begin
     begin transaction
     declare @myError int;
     set @myError = 0;
         update bank set balance=balance + 900 where cid='';
         set @myError += @@ERROR;
         update bank set balance=balance - 900 where cid='';
         set @myError += @@ERROR;
     if(@myError > 0)
     begin
         rollback transaction;
     end
     else
     begin
         commit transaction;
     end
 end;
 go

 select * from bank;

 exec usp_Test;

建个有参数的存储过程,继续转账:

 create proc usp_ZZ2
 @from char(4),  --从那里转
 @to char(4),        --转到哪里
 @money money  --金额
 as
 begin
     begin transaction
     declare @myError int;
     set @myError = 0;
         update bank set balance=balance - @money where cid=@from;
         set @myError += @@ERROR;
         update bank set balance=balance + @money where cid=@to;
         set @myError += @@ERROR;
     -- 什么时候提交，什么时候回滚？
     if(@myError > 0)
     begin
         rollback transaction;
     end
     else
     begin
         commit transaction;
     end
 end
 go

 select * from bank;

 exec usp_ZZ2 '', '', 90;

 exec usp_ZZ2 @money=500, @from = '', @to = '';

 exec usp_ZZ2 '', '', 410;

 go    

依然在转账

 create proc usp_ZZ3
 @from char(4),
 @to char(4),
 @money money
 as
 begin
     begin transaction
     declare @last money;
     set @last = (select balance from bank where cId=@from);
     if(@last - 10 >= @money)
     -- bank表里有一个检查约束，余额要大于等于10
     begin
         update bank set balance=balance - @money where cid=@from;
         update bank set balance=balance + @money where cid=@to;
         commit;
         select '转账成功';
     end
     else
     begin
         rollback;
         select '转账失败';
     end
 end
 go

 exec usp_ZZ3 '', '', 900;

 select * from bank;

 给存储过程的参数设置默认值,示例:

 create proc usp_testDefault
 @str nvarchar(50) = '默认值'
 as
     select @str;

 exec usp_testDefault '我是传进来的参数啊';

output参数怎么用,还在转(转账),修改存储过程zz4;

 -- 带有output参数的存储过程

 go

 create proc usp_ZZ4
 @from char(4),
 @to    char(4),
 @money money,
 @state int output
 -- 这个state表示需要在存储过程中赋值，外面使用的参数
 as
 begin
     begin transaction
     declare @last money;
     set @last = (select balance from bank where cId=@from);
     if(@last - 10 >= @money)

     begin
         update bank set balance=balance - @money where cid=@from;
         update bank set balance=balance + @money where cid=@to;
         commit;
         set @state = 1;--1表示转账成功
     end
     else
     begin
         rollback;
         set @state = 0;--转账失败
     end
 end
 go
 ----------------
 -- 使用
 declare @State int;
 exec usp_ZZ4 '', '', 1000, @State output;
 exec usp_ZZ4 @from = '', @to = '', @money = -501, @state = @State output;

 select @State;