Display Google stacked Column chart from Database with Time and ToolTip in ASP.Net

Thanx at dharmendr sir..

I manage to solve my issue with below changes in my code.

For time used datatype as 'timrofday' and for category used focusTarget: 'category'

var options = {
    title: 'London Olympics Medals',
    colors: ['#FFD700', '#C0C0C0', '#8C7853'],
    // This line makes the entire category's tooltip active.
    focusTarget: 'category',
    }

and for time 
var data = new google.visualization.DataTable();
      data.addColumn('timeofday', 'Time of Day');
      data.addColumn('number', 'Emails Received');

      data.addRows([
        [[8, 30, 45], 5],
        [[9, 0, 0], 10]
]);