Change value of HTML5 data attribute from server side (code behind) in ASP.Net

1. Add runat="server" attribute to DIV and give ID.

<div id = "div1" runat = "server" data-href="http://www.aspforums.net/mypage?PID=10"></div>

2. Then access in code behind or database

div1.Attributes["data-href"] = "http://www.aspforums.net/mypage?PID=10";

You need to do this way

HTML

<div id="div1" runat="server">
</div>

 C#

protected void Page_Load(object sender, EventArgs e)
{
    //Set it from Database, Here i have set the property with hard coded value.
    this.PID = 1;
    div1.Attributes["data-href"] = string.Format("http://www.aspforums.net/mypage?PID={0}", this.PID);
}

Screenshot