OAUTH2.0 to access Google Calendar

using Google.Apis.Auth.OAuth2;
using Google.Apis.Calendar.v3;
using Google.Apis.Calendar.v3.Data;
using Google.Apis.Services;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;

namespace DotNetGoogleCalendarIntegration
{
    class Program
    {
//I just include calendar scope here because i want to access 
//user calendar for event retrieval and insertion
static string[] Scopes = { CalendarService.Scope.Calendar };
static string Applicationname = "Faith Application";
static void Main(string[] args)
{
UserCredential credential;
CalendarService service;
//JSON File created in Google console and added to application folder
using (var stream = new FileStream("..\\..\\googleclient_secret.json",
 FileMode.Open, FileAccess.Read))
{  
    credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
GoogleClientSecrets.Load(stream).Secrets,
      Scopes,
      Environment.UserName,
      CancellationToken.None,
      new DatabaseStore(@"Database Server Name", "database username",
 "password", "databasename", "tablename")).Result;
 //oauth sucks need to get refresh token and save it for persistence and
     to avoid popup dialog every time for ACCEPT and DENY
    // Console.WriteLine(credential);      

}
// Create Calendar Service.
service = new CalendarService(new BaseClientService.Initializer()
{
    HttpClientInitializer = credential,
    ApplicationName = Applicationname ,
});

// Define parameters of request.
EventsResource.ListRequest request = service.Events.List("primary");
request.TimeMin = DateTime.Now;
request.ShowDeleted = false;
request.SingleEvents = true;
request.MaxResults = 10;
request.OrderBy = EventsResource.ListRequest.OrderByEnum.StartTime;
Console.WriteLine("Upcoming events for Shabir:");
Console.WriteLine("====================================================");
Events events = request.Execute();
if (events.Items.Count > 0)
{
    foreach (var eventItem in events.Items)
    {
string when = eventItem.Start.DateTime.ToString();
string title = eventItem.Description.ToString();
string organizer = eventItem.Organizer.Email.ToString();
if (String.IsNullOrEmpty(when))
{
when = eventItem.Start.Date;
}
Console.WriteLine("{0}" + Environment.NewLine + "{1}" + Environment.NewLine + " 
 {2}" + Environment.NewLine + "   {3}", eventItem.Summary, when, title, organizer);
Console.WriteLine("------------------------------------------------------");
    }

}
else
{
    Console.WriteLine("No upcoming events found.");
}

//ADDING EVENT
Event newEvent = new Event();
newEvent.Summary = "Shabir Meeting";
newEvent.Description = "Today going to discuss regarding OAuth Protocol";
newEvent.Start = new EventDateTime();
newEvent.Start.DateTime = DateTime.Now.AddHours(5);
newEvent.End = new EventDateTime();
newEvent.End.DateTime = DateTime.Now.AddHours(8);
service.Events.Insert(newEvent, "primary").ExecuteAsync();
Console.Read();
}
    }
}

//Note: In Case you are looking for saving in local file, i mean implementing IFileDataDtore change above function code snippet with
credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
GoogleClientSecrets.Load(stream).Secrets,
      Scopes,
      Environment.UserName,
      CancellationToken.None,
          CancellationToken.None,
          new FileDataStore(@"D:\CalendarCsharp")).Result;

//DatabaseStore.cs
using Google.Apis.Json;
using Google.Apis.Util.Store;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DotNetGoogleCalendarIntegration
{
    public class DatabaseStore : IDataStore
    {

//database parameters
readonly string tableName;
readonly string serverName;
readonly string loginName;
readonly string passWord;
readonly string databaseName; 
private Boolean _IsConnected { get; set; }
public Boolean connectionAlive { get { return _IsConnected; } }

/// <param name="database">database name
public DatabaseStore(String server, string login, string password, string databasename, string tablename)
{
tableName = tablename;
serverName = server;
loginName = login;
passWord = password;
databaseName = databasename;
SqlConnection myConnection = this.connectdb();   // Opens a connection to the database.
if (_IsConnected)
{
    // check if the Table Exists;
    try
    {
SqlDataReader myReader = null;
SqlCommand myCommand = new SqlCommand("select 1 from GoogleOAuthUser where 1 = 0",myConnection);
myReader = myCommand.ExecuteReader();
while (myReader.Read())
{var hold = myReader["Column1"];}
    }
    catch
    {
// table doesn't exist we create it
SqlCommand myCommand = new SqlCommand("CREATE TABLE [dbo].GoogleOAuthUser( " +
  " username [nvarchar](100) NOT NULL," +
  " RefreshToken [nvarchar](4000) NOT NULL," +
  " Userid [nvarchar](50) NOT NULL" +
   " ) ON [PRIMARY]", myConnection);
myCommand.ExecuteNonQuery();
    }
}

myConnection.Close();
}
/// Stores the given value for the given key. It creates a new 
    ///file (named <see cref="GenerateStoredKey"></see>) in 
<typeparam name="T">///type to store in the data store</typeparam>
/// <param name="key">The key
/// <param name="value">The value to store in the data store
public Task StoreAsync<t>(string key, T value)
{
if (string.IsNullOrEmpty(key))
{
    throw new ArgumentException("Key MUST have a value");
}
var serialized = NewtonsoftJsonSerializer.Instance.Serialize(value);
SqlConnection myConnection = this.connectdb();
if (!_IsConnected)
{
    throw new Exception("Not connected to the database");
}
// Try and find the Row in the DB.
using (SqlCommand command = new SqlCommand
    ("select Userid from GoogleOAuthUser where UserName = @username", myConnection))
{
    command.Parameters.AddWithValue("@username", key);
    string hold = null;
    SqlDataReader myReader = command.ExecuteReader();
    while (myReader.Read())
    {
hold = myReader["Userid"].ToString();
    }
    myReader.Close();
    if (hold == null)
    {
try
{
// New User we insert it into the database
string insertString = "INSERT INTO [dbo].GoogleOAuthUser  (username,RefreshToken,Userid) " +
  " VALUES (@key,@value,'1' )";
SqlCommand commandins = new SqlCommand(insertString, myConnection);
commandins.Parameters.AddWithValue("@key", key);
commandins.Parameters.AddWithValue("@value", serialized);
commandins.ExecuteNonQuery();
}
catch (Exception ex)
{
throw new Exception("Error inserting new row: " + ex.Message);
}
    }
    else
    {
try
{
// Existing User We update it
string insertString = "update GoogleOAuthUser " +
  " set  RefreshToken= @value  " +
  " where username = @key";
SqlCommand commandins = new SqlCommand(insertString, myConnection);
commandins.Parameters.AddWithValue("@key", key);
commandins.Parameters.AddWithValue("@value", serialized);
commandins.ExecuteNonQuery();
}
catch (Exception ex)
{
throw new Exception("Error updating user: " + ex.Message);
}
    }
}
   myConnection.Close();
return TaskEx.Delay(0);
}
/// <summary>
/// Deletes the given key. It deletes the <see cref="GenerateStoredKey"></see>
 /// named file in <see cref="FolderPath"></see>.
/// </summary>
/// <param name="key">The key to delete from the data store
public Task DeleteAsync<t>(string key)
{
if (string.IsNullOrEmpty(key))
{
    throw new ArgumentException("Key MUST have a value");
}
SqlConnection myConnection = this.connectdb();
if (!_IsConnected)
{
    throw new Exception("Not connected to the database");
}
// Deletes the users data.
string deleteString = "delete GoogleOAuthUser from " +
  " where username = @key";
SqlCommand commandins = new SqlCommand(deleteString, myConnection);
commandins.Parameters.AddWithValue("@key", key);
commandins.ExecuteNonQuery();
myConnection.Close();
return TaskEx.Delay(0);
}
public Task<t> GetAsync<t>(string key)
{
//Key is the user string sent with AuthorizeAsync
if (string.IsNullOrEmpty(key))
{
throw new ArgumentException("Key MUST have a value");}
TaskCompletionSource<t> tcs = new TaskCompletionSource<t>();
ConnectionStringSettings mySetting = ConfigurationManager.ConnectionStrings["strSqlConnection"];
if (mySetting == null || string.IsNullOrEmpty(mySetting.ConnectionString))
    throw new Exception("Fatal error: missing connecting string in web.config file");
string connString = mySetting.ConnectionString;
   SqlConnection objConn = new SqlConnection(connString);
objConn.Open();
// Try and find the Row in the DB.
using (SqlCommand command = new SqlCommand("select RefreshToken from GoogleOAuthUser 
    where UserName = @username;", objConn))
{
    command.Parameters.AddWithValue("@username", key);
    string RefreshToken = null;
    SqlDataReader myReader = command.ExecuteReader();
    while (myReader.Read())    {
RefreshToken = myReader["RefreshToken"].ToString();
    }
    if (RefreshToken == null)
    {
// we don't have a record so we request it of the user.
tcs.SetResult(default(T));
    }
    else
    {
try
{
// we have it we use that.
tcs.SetResult(NewtonsoftJsonSerializer.Instance.Deserialize<t>(RefreshToken));
}
catch (Exception ex)
{
tcs.SetException(ex);
}
    }
}
return tcs.Task;
}
/// <summary>
/// Clears all values in the data store. 
///This method deletes all files in <see cref="FolderPath"></see>.
/// </summary>
public Task ClearAsync()
{
SqlConnection myConnection = this.connectdb();
if (!_IsConnected)
{
    throw new Exception("Not connected to the database");
}
// Removes all data from the Table.
string truncateString = "truncate table [dbo].GoogleOAuthUser ";
SqlCommand commandins = new SqlCommand(truncateString, myConnection);
commandins.ExecuteNonQuery();
myConnection.Close();
return TaskEx.Delay(0);
}

/// <summary>Creates a unique stored key based on the key and the class type.</summary>
/// <param name="key">The object key
/// <param name="t">The type to store or retrieve
public static string GenerateStoredKey(string key, Type t)
{
return string.Format("{0}-{1}", t.FullName, key);
}
//Handel's creating the connection to the database
private SqlConnection connectdb()
{
ConnectionStringSettings mySetting = ConfigurationManager.ConnectionStrings["strSqlConnection"];
if (mySetting == null || string.IsNullOrEmpty(mySetting.ConnectionString))
    throw new Exception("Fatal error: missing connecting string in web.config file");
string connString = mySetting.ConnectionString;
SqlConnection myConnection = null;
try
{
    myConnection = new SqlConnection(connString);
    try
    {
myConnection.Open();  
if (myConnection.State == System.Data.ConnectionState.Open)
{
_IsConnected = true;
}
else
{
throw new ArgumentException("Error unable to open connection to the database.");
}
    }
    catch (Exception ex)
    {
throw new ArgumentException("Error opening Connection to the database: " + ex.Message);
    }

}
catch (Exception ex)
{
    throw new ArgumentException("Error creating Database Connection: " + ex.Message);
}

return myConnection;
}

    }
}

 //   // Create Calendar Service.
service = new CalendarService(new BaseClientService.Initializer()
{
    HttpClientInitializer = credential,
    ApplicationName = ApplicationName,
});

// Define parameters of request.
EventsResource.ListRequest request = service.Events.List("primary");
request.TimeMin = DateTime.Now;
request.ShowDeleted = false;
request.SingleEvents = true;
request.MaxResults = 10;
request.OrderBy = EventsResource.ListRequest.OrderByEnum.StartTime;
Console.WriteLine("Upcoming events for Shabir:");
Console.WriteLine("====================================================");
Events events = request.Execute();
if (events.Items.Count > 0)
{
    foreach (var eventItem in events.Items)
    {
string when = eventItem.Start.DateTime.ToString();
string title = eventItem.Description.ToString();
string organizer = eventItem.Organizer.Email.ToString();
if (String.IsNullOrEmpty(when))
{
when = eventItem.Start.Date;
}
Console.WriteLine("{0}" + Environment.NewLine + "{1}" + Environment.NewLine + "  
     {2}" + Environment.NewLine + "   {3}", eventItem.Summary, when, title, organizer);
Console.WriteLine("------------------------------------------------------");
    }

}
else
{
    Console.WriteLine("No upcoming events found.");
}