C++ builder学习之用存储过程实现防止同一个人重复登陆!

本文介绍了一个SQL存储过程用于创建临时表并检查用户登录状态的方法。通过存储过程检查是否已有相同用户名在线，若不存在则允许创建新的会话。文章还提供了一段Delphi风格的代码示例来调用该存储过程。

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//存储过程

/*if Exists(select name from sysobjects where name='addOneArticle' and type='P') drop procedure addOneArticle*/
/*if Exists(select name from sysobjects where name ='Session' and type='P') drop procedure Session*/
   /* exec('drop procedure dbo.Session') */
use highway_test_new
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
if Exists(select id from dbo.sysobjects where id = object_id('dbo.Session') and type = 'P')
BEGIN
   exec('drop procedure dbo.Session')
   return
END

GO
CREATE PROCEDURE Session
    @username varchar(50) ,@i_result INT OUTPUT
AS
BEGIN
    DECLARE @v_sql varchar(200)
    if object_id('tempdb.dbo.##user'+ @username) is null
          begin
             set @v_sql = 'create table ##user'+@username +'(username varchar(100))'
             exec(@v_sql)
             set @i_result = 0
          end
    else
             set @i_result = 1
END
   //

实现代码

bool VerifyUserLogin(TMSConnection* pConn,TMSStoredProc* ptsp,AnsiString strUserName)
{
     if(pConn == NULL || ptsp == NULL)
         return false;
     ptsp->StoredProcName = "Session";
     ptsp->Connection = pConn;
     ptsp->ParamByName("@username")->AsString = strUserName;
     ptsp->ExecProc();
     int iRet ;
     iRet = ptsp->ParamByName("@i_result")->AsInteger;
     if(iRet == 1)//存在相同用户在登陆
     {
        return false;
     }
     else if(iRet == 0)
     {
         return true;
     }
     return false;
}