private void LoadIssueByStatus()
        {
            string        status        = cb_search_issue.SelectedItem.ToString().Trim();
            IssueControls issueControls = new IssueControls();

            if (status.Equals("Expired"))
            {
                List <Issue> allIssue     = issueControls.LoadIssuesByStatus("Expired");
                List <Issue> expiredIssue = new List <Issue>();
                foreach (Issue i in allIssue)
                {
                    if (i.Status.Equals("Expired"))
                    {
                        expiredIssue.Add(i);
                    }
                }
                gv_info_issue.DataSource = expiredIssue;
            }
            else if (status.Equals("Returned"))
            {
                gv_info_issue.DataSource = issueControls.LoadIssuesByStatus(status);
            }
            else
            {
                List <Issue> allIssue    = issueControls.LoadIssuesByStatus(status);
                List <Issue> issuedIssue = new List <Issue>();
                foreach (Issue i in allIssue)
                {
                    if (i.Status.Equals("Issued"))
                    {
                        issuedIssue.Add(i);
                    }
                }
                gv_info_issue.DataSource = issuedIssue;
            }
        }
        private void btn_book_enter_issue_Click(object sender, EventArgs e)
        {
            string sid = tb_book_id_issue.Text.ToString().Trim();

            if (isValidString(sid))
            {
                int          id           = int.Parse(sid);
                BookControls bookControls = new BookControls();
                Book         book         = bookControls.SearchBook(id);
                if (book != null)
                {
                    IssueControls issueControls = new IssueControls();
                    List <Issue>  allIssue      = issueControls.LoadIssuesByStatus("Issued");
                    List <Issue>  issuedIssue   = new List <Issue>();
                    foreach (Issue i in allIssue)
                    {
                        if (i.Status.Equals("Issued"))
                        {
                            issuedIssue.Add(i);
                        }
                    }
                    int count = 0;
                    foreach (Issue i in issuedIssue)
                    {
                        if (i.BookId == id)
                        {
                            count++;
                        }
                    }
                    int total = book.Stock - count;
                    lbl_book_info_issue.Text = "Total Book Remained: " + total;
                    if (total > 0)
                    {
                        btn_add_issue.Enabled        = true;
                        tb_book_id_issue.Enabled     = false;
                        btn_book_enter_issue.Enabled = false;
                    }
                }
                else
                {
                    MessageBox.Show("No Book Found.");
                }
            }
            else
            {
                MessageBox.Show("Please Enter Book Id.");
            }
        }