没什么区别

添加数据库：
protected void Button3_Click(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection("Data Source=PC-20090625YLJF\\SQLEXPRESS;Initial Catalog=user;Integrated Security=True");
        SqlCommand cmd=new SqlCommand("insert into tt(username)  values('"+TextBox3.Text.Trim()+"')",conn);
        conn.Open();
        try{
        int i=cmd.ExecuteNonQuery();
            if(i==1){
            Response.Write("<script>alert('success!')</script>");
            }
            else{
            Response.Write("<script>alert('fail!')</script>");
            }
        }
        catch(Exception ex){
        throw ex;

        }
        finally{
        if(conn.State==ConnectionState.Open)
            conn.Close();
        }
    }