Convert datatable to json in C#

/////////////// Data table to Json String

public String Convert_DataTable_jSonString(DataTable dataTable)

{   

System.Web.Script.Serialization.JavaScriptSerializer serializer =  new System.Web.Script.Serialization.JavaScriptSerializer();   

List<Dictionary<String, Object>> tableRows = new List<Dictionary<String, Object>>(); 

 Dictionary<String, Object> row;

  foreach (DataRow dr in dataTable.Rows)

  {      row = new Dictionary<String, Object>();

      foreach (DataColumn col in dataTable.Columns)     

     {         

        row.Add(col.ColumnName, dr[col]);       

        }       

tableRows.Add(row); 

}   

return  serializer.Serialize(tableRows);

}

///////////////////////// Get data from database

public DataTable GetDataTable()

{   DataTable dataTable = new DataTable();   

using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["dbConString"].ConnectionString))  

{

       SqlCommand cmd = conn.CreateCommand();       

        cmd.CommandText = "Customer_Search";

        cmd.CommandType = CommandType.StoredProcedure;       

        cmd.Parameters.AddWithValue("@City", txtCity.Text);

        if (conn.State != ConnectionState.Open)           

              conn.Open();       

          SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

        dataTable.Load(dr);

} 

return dataTable; 

}

/////////////////////////// Generate Json Stirng

protected void Button1_Click(object sender, EventArgs e)

{

     DataTable dataTable = GetDataTable();     

     String jSonString = ConvertDataTableTojSonString(dataTable);

}