private void btnOK_Click(object sender, EventArgs e)
        {
            DatabaseObjectType databaseObjectType = DatabaseObjectType.None;

            foreach (var item in this.chkDbObjectTypes.CheckedItems)
            {
                DatabaseObjectType type = (DatabaseObjectType)Enum.Parse(typeof(DatabaseObjectType), ManagerUtil.GetSingularString(item.ToString()));

                databaseObjectType = databaseObjectType | type;
            }

            if (databaseObjectType == DatabaseObjectType.None)
            {
                MessageBox.Show("Please select database object type.");
                return;
            }
            else
            {
                this.DatabaseObjectType = databaseObjectType;
            }

            this.DialogResult = DialogResult.OK;

            this.Close();
        }