使用 C# 从 ASP.NET 中的 SQL Server 检索数据

Question

I have successfully created a master page to upload and edit data and has successfully retrieved that data at my client page, homepage. Now here is my problem, in my homepage I have 5 repeaters retrieving data from 5 tables both text and image:

• Home page slider
• News
• Feature Post
• Principal Notes
• About the College

Here is my code for retrieving the data:

private DataTable GetData(string query)
{
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;

    SqlCommand cmd = new SqlCommand(query);

    using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlDataAdapter sda = new SqlDataAdapter())
        {
            cmd.Connection = con;
            sda.SelectCommand = cmd;

            using (DataTable dt = new DataTable())
            {
                sda.Fill(dt);
                return dt;
            }
        }
    }
}

private void rpt_slider()
{
    try
    {
        DataTable dt1 = this.GetData("select top(5)* from H_slide");
        rpt_sli.DataSource = dt1;
        rpt_sli.DataBind();
    }
    catch (Exception)
    {
    }
}

And on page load:

protected void Page_Load(object sender, EventArgs e)
{    
    // homepage slider
    rpt_slider();

    // news
    rpt_news();

    // featured post
    rpt_feat();

    // principal notes
    rpt_notes();

    // about college
    rpt_about();
}

Retrieving all that data takes a lot of time, especially if the internet speed is slow. So is it possible to retrieve the data one by one? First the homepage slider and after a few seconds the news data and after that about the college and so on so that all the data is not loaded at once but at intervals of few seconds. I have spent days researching but have not found any solution, I don't know if it's possible to do that but if there is any solution will anyone please help me.

Thank you.

Answer 1

I am afraid this is a little more involved than you think. If you need everything on the same page, you will have to get them using AJAX: Get the first set and once the response has returned, then send the subsequent request. Here is an article you can follow. But like I said, it is more involved than you think.

Also, try and using paging. For example, if one of your tables has 1 million rows, do not get all 1 million. Get maybe 50 and have controls so users can press next and then get the next 50 and so on. Here is a tutorial that you can follow for paging, sorting etc.

Answer 2

Rather it's really simple, in my humble opinion. Use task parallel library (this needs .NET 4.5), if the 5 types of data are independent of each other. Get all these data asynchronously from db and bind them to repeaters. This should show you a big performance gain.

Also follow the suggestions of paging suggested by @codingyoshi.

If this performance improvement isn't enough , come back, I will suggest some other changes.

Code example:

Parallel.Invoke{()=>(
{
    // homepage slider
    rpt_slider();

},
{
    // news
    rpt_news();    
},
{
   // featured post
   rpt_feat();


},
{
    // principal notes
    rpt_notes();    
},
{
    // about college
    rpt_about();
}

)};