Add new event when Click on Calendar Day using C# and VB.Net in ASP.Net

Hi sani.ss501,

Check this example. Now please take its reference and correct your code.

HTML

<asp:TextBox ID="txtEventDesc" runat="server" />
<asp:Calendar ID="Calendar1" runat="server" OnSelectionChanged="Clicked" OnDayRender="Calendar1_DayRender"
    ShowGridLines="True"></asp:Calendar>

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Web.UI.WebControls;

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.UI.WebControls

Code

C#

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
{
    System.Data.DataTable dt = GetEvents();
    foreach (System.Data.DataRow row in dt.Rows)
    {
        if (Convert.ToDateTime(e.Day.Date) == Convert.ToDateTime(row["Date"]))
        {
            e.Cell.Controls.Add(new Label { Text = "<br/>" });
            e.Cell.Controls.Add(new Label { Text = row["Desc"].ToString() });
        }
    }
}

private System.Data.DataTable GetEvents()
{
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    string query = "SELECT Desc,Date FROM Events";
    SqlCommand cmd = new SqlCommand(query);
    using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlDataAdapter sda = new SqlDataAdapter())
        {
            cmd.Connection = con;
            sda.SelectCommand = cmd;
            using (DataTable dt = new DataTable())
            {
                sda.Fill(dt);
                return dt;
            }
        }
    }
}

protected void Clicked(object sender, EventArgs e)
{
    string desc = GetEventDesc((sender as Calendar).SelectedDate);
    if (string.IsNullOrEmpty(desc))
    {
        string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        string query = "INSERT INTO Events VALUES(@Desc,@Date)";
        SqlCommand cmd = new SqlCommand(query);
        using (SqlConnection con = new SqlConnection(conString))
        {
            cmd.Connection = con;
            cmd.Parameters.AddWithValue("@Desc", txtEventDesc.Text);
            cmd.Parameters.AddWithValue("@Date", (sender as Calendar).SelectedDate);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
    else
    {
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('" + desc + "')", true);
    }
}

private string GetEventDesc(DateTime eventDate)
{
    string eventDesc = "";
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    string query = "SELECT Desc FROM Events WHERE Date=@Date";
    SqlCommand cmd = new SqlCommand(query);
    using (SqlConnection con = new SqlConnection(conString))
    {
        cmd.Connection = con;
        cmd.Parameters.AddWithValue("@Date", eventDate);
        con.Open();
        eventDesc = Convert.ToString(cmd.ExecuteScalar());
        con.Close();
    }

    return eventDesc;
}

VB.Net

Protected Sub Calendar1_DayRender(ByVal sender As Object, ByVal e As DayRenderEventArgs)
    Dim dt As System.Data.DataTable = GetEvents()
    For Each row As System.Data.DataRow In dt.Rows
        If Convert.ToDateTime(e.Day.Date) = Convert.ToDateTime(row("Date")) Then
            e.Cell.Controls.Add(New Label With {.Text = "<br/>"})
            e.Cell.Controls.Add(New Label With {.Text = row("Desc").ToString()})
        End If
    Next
End Sub

Private Function GetEvents() As System.Data.DataTable
    Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Dim query As String = "SELECT Desc,Date FROM Events"
    Dim cmd As SqlCommand = New SqlCommand(query)
    Using con As SqlConnection = New SqlConnection(conString)
        Using sda As SqlDataAdapter = New SqlDataAdapter()
            cmd.Connection = con
            sda.SelectCommand = cmd
            Using dt As DataTable = New DataTable()
                sda.Fill(dt)
                Return dt
            End Using
        End Using
    End Using
End Function

Protected Sub Clicked(ByVal sender As Object, ByVal e As EventArgs)
    Dim desc As String = GetEventDesc((TryCast(sender, Calendar)).SelectedDate)
    If String.IsNullOrEmpty(desc) Then
        Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Dim query As String = "INSERT INTO Events VALUES(@Desc,@Date)"
        Dim cmd As SqlCommand = New SqlCommand(query)
        Using con As SqlConnection = New SqlConnection(conString)
            cmd.Connection = con
            cmd.Parameters.AddWithValue("@Desc", txtEventDesc.Text)
            cmd.Parameters.AddWithValue("@Date", (TryCast(sender, Calendar)).SelectedDate)
            con.Open()
            cmd.ExecuteNonQuery()
            con.Close()
        End Using
    Else
        ClientScript.RegisterClientScriptBlock(Me.GetType(), "", "alert('" & desc & "')", True)
    End If
End Sub

Private Function GetEventDesc(ByVal eventDate As DateTime) As String
    Dim eventDesc As String = ""
    Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Dim query As String = "SELECT Desc FROM Events WHERE Date=@Date"
    Dim cmd As SqlCommand = New SqlCommand(query)
    Using con As SqlConnection = New SqlConnection(conString)
        cmd.Connection = con
        cmd.Parameters.AddWithValue("@Date", eventDate)
        con.Open()
        eventDesc = Convert.ToString(cmd.ExecuteScalar())
        con.Close()
    End Using

    Return eventDesc
End Function