While working with the data whether its from external source or it is from the datasource which is local you need to do parsing for it.

The process of serialization of data and deserialization of data is totally based on it.

So for doing that can be done in many ways here we are using the serialize function for making the conversion into the JSON form.

 public string ConvertDataTabletoString()
    {
        DataTable dt = new DataTable();
        using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnectionString"].ConnectionString))
        {
            using (SqlCommand cmd = new SqlCommand("select title=Company,lat=latitude,lng=longitude,image from MapDimension", con))
            {
                con.Open();
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(dt);
                System.Web.Script.Serialization.JavaScriptSerializer serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
                List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
                Dictionary<string, object> row;
                foreach (DataRow dr in dt.Rows)
                {
                    row = new Dictionary<string, object>();
                    foreach (DataColumn col in dt.Columns)
                    {
                        row.Add(col.ColumnName, dr[col]);
                    }
                    rows.Add(row);
                }
                return serializer.Serialize(rows);
            }
        }