Asp.Net 弹出对话框，提示用户

if (read.HasRows)

            {

           Response.Write("<script language=javascript>alert( '该用户已注册！');window.location.href='StuInsert.aspx';</script>");

或者

           System.Web.UI.Page.ClientScript.RegisterStartupScript(System.Web.UI.Page.GetType(), "message", "<script language='javascript' defer>alert('该用户已注册！');location.href='StuInsert.aspx'</script>");

或者

             page.ClientScript.RegisterStartupScript(System.Web.UI.Page.GetType(), "message", "<script language='javascript' defer>alert('该用户已注册！');location.href='StuInsert.aspx'</script>");

       }

先弹出已经注册，再回到你本页