Upload specific files' types into database

protected void btnUpload_Click(object sender, EventArgs e)
{
    //Check whether FileUpload control has file
    if (FileUpload1.HasFile)
    {
        string fileName = Path.GetFileName(FileUpload1.PostedFile.FileName);
        string fileExtension = Path.GetExtension(FileUpload1.PostedFile.FileName);
        string documentType = string.Empty;

        //provide document type based on it's extension
        switch (fileExtension)
        {
            case ".pst":
                documentType = "application/pst";
                break;
            case ".pdf":
                documentType = "application/pdf";
                break;
            case ".xls":
                documentType = "application/vnd.ms-excel";
                break;
            case ".xlsx":
                documentType = "application/vnd.ms-excel";
                break;
            case ".jpg":
                documentType = "image/jpg";
                break;
        }

        //Calculate size of file to be uploaded
        int fileSize = FileUpload1.PostedFile.ContentLength;

        //Create array and read the file into it
        byte[] documentBinary = new byte[fileSize];
        FileUpload1.PostedFile.InputStream.Read(documentBinary, 0, fileSize);

        // Create SQL Connection
        SqlConnection con = new SqlConnection();
        con.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

        // Create SQL Command and Sql Parameters
        SqlCommand cmd = new SqlCommand();
        cmd.CommandText = "INSERT INTO SaveDoc(DocName,Type,DocData)" +
                          " VALUES (@DocName,@Type,@DocData)";
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;

        SqlParameter DocName = new SqlParameter("@DocName", SqlDbType.VarChar, 50);
        DocName.Value = fileName.ToString();
        cmd.Parameters.Add(DocName);

        SqlParameter Type = new SqlParameter("@Type", SqlDbType.VarChar, 50);
        Type.Value = documentType.ToString();
        cmd.Parameters.Add(Type);

        SqlParameter uploadedDocument = new SqlParameter("@DocData", SqlDbType.Binary,fileSize);
        uploadedDocument.Value = documentBinary;
        cmd.Parameters.Add(uploadedDocument);

        con.Open();
        int result = cmd.ExecuteNonQuery();
        con.Close();
        if (result > 0)
            lblMessage.Text = "File saved to database";
        GridView1.DataBind();
    }
}

<div>
<asp:FileUpload ID="FileUpload1" runat="server"/>
<asp:Button ID="btnUpload" runat="server"  
            onclick="btnUpload_Click" 
            Text="Upload"/>
</div>