// Event handler for ImageButton .
        public virtual void UOMExportExcelButton_Click(object sender, ImageClickEventArgs args)
        {
            try {
                // Enclose all database retrieval/update code within a Transaction boundary
                DbUtils.StartTransaction();

            // To customize the columns or the format, override this function in Section 1 of the page
            // and modify it to your liking.
            // Build the where clause based on the current filter and search criteria
            // Create the Order By clause based on the user's current sorting preference.

                WhereClause wc = null;
                wc = CreateWhereClause();
                OrderBy orderBy = null;

                orderBy = CreateOrderBy();

              bool done = false;
              string val = "";
              CompoundFilter join = CreateCompoundJoinFilter();

              // Read pageSize records at a time and write out the Excel file.
              int totalRowsReturned = 0;

              this.TotalRecords = UOMTable.GetRecordCount(join, wc);
              if (this.TotalRecords > 10000)
              {

                // Add each of the columns in order of export.
                BaseColumn[] columns = new BaseColumn[] {
                             UOMTable.UOMName,
             UOMTable.UOMDescription,
             UOMTable.Status,
             null};
                ExportDataToCSV exportData = new ExportDataToCSV(UOMTable.Instance,wc,orderBy,columns);
                exportData.StartExport(this.Page.Response, true);

                DataForExport dataForCSV = new DataForExport(UOMTable.Instance, wc, orderBy, columns,join);

                //  Read pageSize records at a time and write out the CSV file.
                while (!done)
                {
                ArrayList recList = dataForCSV.GetRows(exportData.pageSize);
                if (recList == null)
                break; //we are done

                totalRowsReturned = recList.Count;
                foreach (BaseRecord rec in recList)
                {
                foreach (BaseColumn col in dataForCSV.ColumnList)
                {
                if (col == null)
                continue;

                if (!dataForCSV.IncludeInExport(col))
                continue;

                val = rec.GetValue(col).ToString();
                exportData.WriteColumnData(val, dataForCSV.IsString(col));
                }
                exportData.WriteNewRow();
                }

                //  If we already are below the pageSize, then we are done.
                if (totalRowsReturned < exportData.pageSize)
                {
                done = true;
                }
                }
                exportData.FinishExport(this.Page.Response);

              }
              else
              {
              // Create an instance of the ExportDataToExcel class with the table class, where clause and order by.
              ExportDataToExcel excelReport = new ExportDataToExcel(UOMTable.Instance, wc, orderBy);
              // Add each of the columns in order of export.
              // To customize the data type, change the second parameter of the new ExcelColumn to be
              // a format string from Excel's Format Cell menu. For example "dddd, mmmm dd, yyyy h:mm AM/PM;@", "#,##0.00"

              if (this.Page.Response == null)
              return;

              excelReport.CreateExcelBook();

              int width = 0;
              int columnCounter = 0;
              DataForExport data = new DataForExport(UOMTable.Instance, wc, orderBy, null,join);
                           data.ColumnList.Add(new ExcelColumn(UOMTable.UOMName, "Default"));
             data.ColumnList.Add(new ExcelColumn(UOMTable.UOMDescription, "Default"));
             data.ColumnList.Add(new ExcelColumn(UOMTable.Status, "Default"));

              //  First write out the Column Headers
              foreach (ExcelColumn col in data.ColumnList)
              {
              width = excelReport.GetExcelCellWidth(col);
              if (data.IncludeInExport(col))
              {
              excelReport.AddColumnToExcelBook(columnCounter, col.ToString(), excelReport.GetExcelDataType(col), width, excelReport.GetDisplayFormat(col));
//.........这里部分代码省略.........

        public static string GetSum(
		BaseColumn col,
		BaseFilter join, 
		WhereClause where,
		OrderBy orderBy,
		int pageIndex,
		int pageSize)
        {
            SqlBuilderColumnSelection colSel = new SqlBuilderColumnSelection(false, false);
            colSel.AddColumn(col, SqlBuilderColumnOperation.OperationType.Sum);

            return UsersTable.Instance.GetColumnStatistics(colSel, join, where.GetFilter(), null, orderBy, pageIndex, pageSize);
        }

        public static String[] GetValues(
		BaseColumn col,
		BaseFilter join,
		WhereClause where,
		OrderBy orderBy,
		int maxItems)
        {
            // Create the filter list.
            SqlBuilderColumnSelection retCol = new SqlBuilderColumnSelection(false, true);
            retCol.AddColumn(col);

            return UsersTable.Instance.GetColumnValues(retCol, join, where.GetFilter(), null, orderBy, BaseTable.MIN_PAGE_NUMBER, maxItems);
        }

        /// <summary>
        /// This method takes a record and a Column and returns an evaluated value of DFKA formula.
        /// </summary>
        public static string GetDFKA(BaseRecord rec, BaseColumn col)
        {
            ForeignKey fkColumn = UsersTable.Instance.TableDefinition.GetExpandableNonCompositeForeignKey(col);
            if (fkColumn == null)
                return null;
            String _DFKA = fkColumn.PrimaryKeyDisplayColumns;
            if (_DFKA.Trim().StartsWith("="))
            {
                // if the formula is in the format of "= <Primary table>.<Field name>, then pull out the data from the rec object instead of doing formula evaluation
                string tableCodeName = fkColumn.PrimaryKeyTableDefinition.TableCodeName;
                string column = _DFKA.Trim('=').Trim();
                if (column.StartsWith(tableCodeName + ".", StringComparison.InvariantCultureIgnoreCase))
                {
                    column = column.Substring(tableCodeName.Length + 1);
                }

                foreach (BaseColumn c in fkColumn.PrimaryKeyTableDefinition.Columns)
                {
                    if (column == c.CodeName)
                    {
                        return rec.Format(c);
                    }
                }

                String tableName = fkColumn.PrimaryKeyTableDefinition.TableCodeName;
                return EvaluateFormula(_DFKA, rec, null, tableName);
            }
            else
                return null;
        }

 public ExportData(BaseTable tbl, WhereClause wc, OrderBy orderBy, BaseColumn[] columns)
 {
     _exportDataToCSV = new ExportDataToCSV(tbl, wc, orderBy, columns);
 }

        public static string GetCount(
		BaseColumn col,
		WhereClause where,
		OrderBy orderBy,
		int pageIndex,
		int pageSize)
        {
            SqlBuilderColumnSelection colSel = new SqlBuilderColumnSelection(false, false);
            colSel.AddColumn(col, SqlBuilderColumnOperation.OperationType.Count);

            return EstimateTable.Instance.GetColumnStatistics(colSel, null, where.GetFilter(), null, orderBy, pageIndex, pageSize);
        }

        public string GetDataForExport(BaseColumn col, BaseRecord rec)
        {
            String val = "";

            if (col.TableDefinition.IsExpandableNonCompositeForeignKey(col))
            {
                //  Foreign Key column, so we will use DFKA and String type.
                val = rec.Format(col);
            }
            else
            {
                switch (col.ColumnType)
                {
                    case BaseColumn.ColumnTypes.Binary:
                    case BaseColumn.ColumnTypes.Image:
                        break;
                    case BaseColumn.ColumnTypes.Currency:
                    case BaseColumn.ColumnTypes.Number:
                    case BaseColumn.ColumnTypes.Percentage:
                        val = rec.Format(col);
                        break;
                    default:
                        val = rec.Format(col);
                        break;
                }
            }
            return val;
        }

 /// <summary>
 /// Cretes new ExcelColumn
 /// </summary>
 /// <param name="col">BaseColumn</param>
 /// <param name="format">a format string from Excel's Format Cell menu. For example "dddd, mmmm dd, yyyy h:mm AM/PM;@", "#,##0.00"</param>
 public ExcelColumn(BaseColumn col, string format)
 {
     DisplayColumn = col;
         DisplayFormat = format;
 }

 public ExportDataToCSV(BaseTable tbl, WhereClause wc, OrderBy orderBy, BaseColumn[] columns, String header)
     : base(header)
 {
     data = new DataForExport(tbl, wc, orderBy, columns);
 }

        public bool IsString(BaseColumn col)
        {
            if (col == null)
                return false;

            switch (col.ColumnType)
            {
                case BaseColumn.ColumnTypes.Binary:
                case BaseColumn.ColumnTypes.Image:
                case BaseColumn.ColumnTypes.Currency:
                case BaseColumn.ColumnTypes.Number:
                case BaseColumn.ColumnTypes.Percentage:
                    return false;
            }
            return true;
        }

        public bool IncludeInExport(BaseColumn col)
        {
            if (col == null)
                return false;

            switch (col.ColumnType)
            {
                case BaseColumn.ColumnTypes.Binary:
                case BaseColumn.ColumnTypes.Image:
                    //  Skip - do nothing for these columns
                    return false;
            }
            return true;
        }

 public DataForExport(BaseTable tbl, WhereClause wc, OrderBy orderBy, BaseColumn[] columns, BaseFilter join)
 {
     this.DBTable = tbl;
     this.SelectWhereClause = wc;
     this.SelectOrderBy = orderBy;
     this.SelectJoin = join;
     if (columns != null)
         ColumnList.AddRange(columns);
 }

        public static string GetSum(
		BaseColumn col,
		WhereClause where,
		OrderBy orderBy,
		int pageIndex,
		int pageSize)
        {
            SqlBuilderColumnSelection colSel = new SqlBuilderColumnSelection(false, false);
            colSel.AddColumn(col, SqlBuilderColumnOperation.OperationType.Sum);

            return VwPropSBondBudgetView.Instance.GetColumnStatistics(colSel, null, where.GetFilter(), null, orderBy, pageIndex, pageSize);
        }