how to clear html table contents?

Hi, All,
I wrote code to create a dynamic html table with three columns contents, session date, title and location. I need to pass different sql string to display different search results. But it looks like my code doesn't work the way it is supposed to be - the table always displays the original results. Here is my code:
protected void loadTbl(string sql)
        {
         
            string trHead = "";
            string strConn = ConfigurationManager.ConnectionStrings["myconnectionstr"].ConnectionString;


            SqlConnection conn = new SqlConnection(strConn);
            SqlCommand cmd = new SqlComma ...