private void btnBuild_Click(object sender, EventArgs e)
        {
            //是否为空
            if (cmbYear.SelectedIndex == -1 || cmbMonth.SelectedIndex == -1 || cmbDepartment.SelectedIndex == -1)
            {
                CommonHelper.FailedReply("不能为空!");
                return;
            }

            int  year    = int.Parse(cmbYear.Text);
            int  month   = int.Parse(cmbMonth.Text);
            Guid depId   = (Guid)cmbDepartment.SelectedValue;
            Guid sheetId = ss.GetSalarySheetId(year, month, depId);


            if (sheetId == Guid.Empty)
            {
                //生成新的工资单
                SalarySheet sheet = new SalarySheet();
                sheet.Id           = Guid.NewGuid();
                sheet.Year         = year;
                sheet.Month        = month;
                sheet.DepartmentId = depId;
                ss.BuildNewSalarySheet(sheet);
                ss.BuildSalaryItems(sheet.Id, depId);
                DataGridView.DataSource = ss.GetSalarySheetItems(sheet.Id);
            }
            else
            {
                //是否重新生成
                DialogResult dr = MessageBox.Show("已经生成该工资表,是否重新生成?", "警告", MessageBoxButtons.YesNo);
                if (dr == DialogResult.Yes)
                {
                    ss.DeleteSalaryItems(sheetId);
                    ss.BuildSalaryItems(sheetId, depId);
                    DataGridView.DataSource = ss.GetSalarySheetItems(sheetId);
                }
                else
                {
                    DataGridView.DataSource = ss.GetSalarySheetItems(sheetId);
                }
            }
        }