?using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class register : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string username1, userpwd1,email1;
        username1 = TextBox1.Text.Trim();
        userpwd1 = TextBox2.Text.Trim(); 
        email1=TextBox3.Text.Trim();
        SqlConnection con = DB.CreateCon();
        con.Open();
        SqlCommand cmd = new SqlCommand("select count(*) from guest where(userName like'" + username1+"')", con);
        int flag=(int)cmd.ExecuteScalar();  
        if (flag == 0) //用戶名不存在
        {     
            SqlCommand cmd1 = new SqlCommand("insert into guest(username,userpwd,email) values ('" + username1 + "','" + userpwd1 + "','" + email1 + "')", con);
            cmd.ExecuteNonQuery();
            con.Close();
            Session["username"] = TextBox1.Text;
            
            Label1.Text = Session["username"].ToString() ;
        }
        else //用戶名已經存在
        {
            Label1.Text = "對不起！用戶名已占用，請選擇其他用戶名！";
            TextBox1.Text = "";
            TextBox2.Text = "";
            TextBox3.Text = "";
        }
    }
}