步步为营-51-存储过程

说明 :存储过程类比C#中的方法

1.1 语法:create procedure 存储过程名称

@变量 类型[=默认值] [output],

@变量 类型[=默认值] [output] ,

...

as

begin

　　内容

end

1.2 创建一个数据表,并添加数据

use DemoDB
create table bank 
(
    cId char(4) primary key not null,
    balance money 
)
insert  into bank (cId,balance) Values('0001',1000);
insert  into bank (cId,balance) Values('0002',10);
select  *　from bank;

1.3 创建存储过程
　　1.3.1 存储过程Version:1.0

--02  创建存储过程 ------
go
create procedure usp_转账_01
as
begin
    --02-01 捕获异常
    begin try
        --02-02 事务通过事务比较好
        begin transaction
            Update bank set balance = balance - 200 where cId = '0001'
            Update bank set balance = balance + 200 where cId = '0002'
        commit transaction
    end try
     
    BEGIN catch
        rollback transaction
    END catch
end

--03 执行存储过程---
exec usp_转账_01;

　　1.3.2 存储过程1.0没有办法指定某个账号及金额,而且也不知道是否转账成功.所以对其进行升级

　　　　1.3.3 添加约束  alter table bank add constraint CK_bank_balance check(balance>0 );　　　　

　　

--02  创建存储过程 ------
go
create procedure usp_转账_02
@from Char(4),
@to char(4),
@money money,
@IsSuccess nvarchar(32) output 
as
begin
    --02-01 捕获异常
    begin try
        --02-02 事务通过事务比较好
        begin transaction
            Update bank set balance = balance - @money where cId = @from
            Update bank set balance = balance + @money where cId = @to
        commit transaction
        set @IsSuccess = '转账成功!'
    end try     
    BEGIN catch
        rollback transaction
        set @IsSuccess = '转账失败!'
    END catch
end

　　

    --03-01 按顺序输入参数
    declare @IsSuccess nvarchar(32)
   exec usp_转账_02 '0001','0002',100, @IsSuccess output;
   select @IsSuccess
       --03-02 按指定内容输入参数
    declare @IsSuccess nvarchar(32)
   exec usp_转账_02 @from='0001',@to='0002',@money=100, @IsSuccess= @IsSuccess output;
   select @IsSuccess

运行结果

执行成功后

再次执行,由于约束限制,执行失败

2.1 存储过程在C#中的调用　　

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ProcedureDemo
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnConfirm_Click(object sender, EventArgs e)
        {
            string connStr = "server=.;uid=sa;pwd =sa;database=DemoDB";
            string from = txtFrom.Text;
            string to = txtTo.Text;
            string money = txtMoney.Text;
            using (SqlConnection conn = new SqlConnection( connStr))
            {
                conn.Open();
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.Connection = conn;

                    //01 将SQLcommand的text文本设置成存储过程的名称
                    cmd.CommandText = "usp_转账_02";
                    //02 设置参数
                    SqlParameter[] sps =
                    {
                        new SqlParameter("@from",from), 
                        new SqlParameter("@to",to), 
                        new SqlParameter("@money",money),
                        //传出参数
                        new SqlParameter("@IsSuccess",SqlDbType.NVarChar,32), 
                    };
                    //指明输出参数
                    sps[3].Direction = ParameterDirection.Output;
                    //03执行SQL语句,所选择的方法根据存储过程的返回值而定,
                    cmd.Parameters.AddRange(sps);

                    cmd.ExecuteNonQuery();

                    MessageBox.Show(sps[3].Value.ToString());
                }
            }

        }
    }
}

运行效果

3.1 job任务用到的存储过程,

　　场景:一张表中存储一个ProcessID和StrSQL语句,每隔一段时间遍历该表进行更新另一张(权限表)

      3.1.1 第一步,先实现传入对应的ProcessID和StrSQL实现更新

ALTER procedure [dbo].[sp_UpdateProcRightsStartUserForJob2]
  
  @ProcID Int,
 @StrSQL varchar(max)

as
begin
 
   
 BEGIN
     
     delete from ProcRightsStartUser where ProcID = @ProcID
      IF OBJECT_ID('tempdb.dbo.#tbl_UserID_Temp','U') IS NOT NULL DROP TABLE dbo.#tbl_UserID_Temp;
     CREATE TABLE #tbl_UserID_Temp (ProcID int,UserID varchar(50) )   --创建一个临时表
     INSERT INTO #tbl_UserID_Temp(UserID) EXEC (@StrSQL)              --StrSQL语句可能获得多行单列数据
     Update #tbl_UserID_Temp set ProcID=@ProcID;
     INSERT INTO ProcRightsStartUser(ProcID,UserID)  select ProcID,UserID from #tbl_UserID_Temp 
     
 END
 
 
          
    
    
end

　　3.1.2 进一步完善

ALTER procedure [dbo].[sp_UpdateProcRightsStartUserForJob]
  
as
begin 
  --01 捕获异常
  begin try
        -- 创建临时表
     IF OBJECT_ID('tempdb.dbo.#devicetemp','U') IS NOT NULL DROP TABLE dbo.#devicetemp; 
     SELECT ProcessID,StrSQL 
     INTO dbo.#devicetemp
    from ProcRightsStartPermission 
     ORDER BY ProcessID;
     -- 声明变量
     DECLARE
         @ProcessID AS INT,
         @StrSQL varchar(max)  
         
     WHILE EXISTS(SELECT ProcessID FROM dbo.#devicetemp)
     BEGIN
         -- 也可以使用top 1
         --SET ROWCOUNT 1
         SELECT @ProcessID=ProcessID, @StrSQL=StrSQL  FROM dbo.#devicetemp;
                --print @StrSQL
            begin transaction           
            delete from ProcRightsStartUser where ProcessID = @ProcessID
             IF OBJECT_ID('tempdb.dbo.#tbl_UserID_Temp','U') IS NOT NULL DROP TABLE dbo.#tbl_UserID_Temp;
            CREATE TABLE #tbl_UserID_Temp (ProcessID int,UserID varchar(50) )
            INSERT INTO #tbl_UserID_Temp(UserID)EXEC (@StrSQL)         
            Update #tbl_UserID_Temp set ProcessID=@ProcessID;
            INSERT INTO ProcRightsStartUser(ProcessID,UserID)  select ProcessID,UserID from #tbl_UserID_Temp 
            commit transaction                         
         SET ROWCOUNT 0
         
         DELETE FROM dbo.#devicetemp WHERE ProcessID=@ProcessID;
     END 
    end try     
    BEGIN catch
        rollback transaction
       -- set @IsSuccess = '失败!'
    END catch
end

3.2 分割字符串进行循环

ALTER procedure [dbo].[sp_UpdateProcRightsStartUser]
 @ProcID Int,
 @UsersID nvarchar(max) --权宜之计
as
begin
    --02-01 捕获异常
    begin try
        --02-02 事务通过事务比较好,如果  1删除数据,2插入数据,  如果插入失败那么也不能删除
        begin transaction
            delete from ProcRightsStartUser where ProcID = @ProcID
            --02-03 按照";"分割字符串
            Begin
                Declare @i Int
                Set @UsersID = RTrim(LTrim(@UsersID))          --去掉字符串变量左右空白
                Set @i = CharIndex(';',@UsersID)             --获取第一个分隔字符所在字符中的索引位置@i
                While @i >= 1                           --while循环，一直到@i=0结束，因为索引为0的话说明字符串中已不存在分隔符
                Begin
                    Insert into ProcRightsStartUser (ProcID,UserID) Values(@ProcID,Left(@UsersID,@i-1))
                    Set @UsersID = SubString(@UsersID,@i+1,Len(@UsersID)-@i)
                    Set @i = CharIndex(';',@UsersID)
                End
                If @UsersID <> ''
                Insert into ProcRightsStartUser (ProcID,UserID) Values(@ProcID,@UsersID)
                --Return
            End         
        commit transaction
       -- set @IsSuccess = '成功!'
    end try     
    BEGIN catch
        rollback transaction
       -- set @IsSuccess = '失败!'
    END catch
end