sql 的数据类型

设字段为 uniqueidentifier 显示为32位的二进制的编码;好处是当几个系统进行整和时id不会发生冲突;8-4-4-4-12组合;

public static Agent CreateAgent(Agent agent)
  {
   IConnection cnn = ConnectionManager.GetConnection();
   cnn.Open();
   ITransaction trans = cnn.BeginTransaction();
   ICommand cmd;
   int i=0;
   int effectedRows = 0;

   Guid agentId = Guid.NewGuid();
   string sql = "INSERT INTO [B2B_Agent]( "
    + " [AgentId], [Code], [Type], [Level],  "
    + " [CompanyName], [CompanyNameShort], [ProvinceCode], [CityCode], "
    + " [Address], [PostCode], [Linkman], [Email], [Tel], "
    + " [MobileTel], [Msn], [QQ], [IsProvider], [IsPurchaser], [State], [RegisterDate], [Introducer], [CommisionMode]) "
    + " VALUES(  "
    + " ?, '', ?, ?, "
    + " ?, ?, ?, ?, "
    + " ?, ?, ?, ?, ?, "
    + " ?, ?, ?, ?, ?, ?, getdate(), '', ?) ";
   cmd = cnn.CreateCommand(sql);
   cmd.Transaction = trans;
   cmd.SetGuid(i, agentId); i++;
   cmd.SetInt(i, agent.Type); i++;
   cmd.SetInt(i, agent.Level); i++;
   cmd.SetNVarChar(i, agent.CompanyName); i++;
   cmd.SetNVarChar(i, agent.CompanyNameShort); i++;
   cmd.SetInt(i, agent.ProvinceCode); i++;
   cmd.SetInt(i, agent.CityCode); i++;
   cmd.SetNVarChar(i, agent.Address); i++;
   cmd.SetVarChar(i, agent.PostCode); i++;
   cmd.SetNVarChar(i, agent.Linkman); i++;
   cmd.SetVarChar(i, agent.Email);i++;
   cmd.SetVarChar(i, agent.Tel); i++;
   cmd.SetVarChar(i, agent.MobileTel); i++;
   cmd.SetVarChar(i, agent.Msn); i++;
   cmd.SetVarChar(i, agent.QQ); i++;
   cmd.SetBit(i, agent.IsProvider); i++;
   cmd.SetBit(i, agent.IsPurchaser); i++;
   cmd.SetInt(i, agent.State); i++;
   cmd.SetInt(i, agent.CommisionMode); i++;
   //cmd.SetBit(i, agent.IsProvider); i++;
   //cmd.SetBit(i, agent.IsPurchaser); i++;

   try
   {
    effectedRows = cmd.ExecuteNonQuery();
   }
   catch(Exception e)
   {
    goto Error;
   }
           
   if (!(effectedRows >0))
   {
    goto Error;
   }

   trans.Commit();
   cnn.Close();
   return GetAgentById(agentId);

   Error:
    trans.Rollback();
   cnn.Close();
   return null;
  } "?" 的作用是防止编码混乱;或者delete table1 where a=1 or 1=1

declare @A varchar set@A='1 or 1=1'
delete table1 where a=@A