如何将数据库中的树结构表导出EXCEL

我们常常会遇到这样的需求，将数据库中父子结构的表数据导出作为表头

我们实现的开发中就遇到这样的需求：将所有用户的权限表导出，权限作为表头

思路：sql求出每一条权限数据应该跨的行数,在代码中填充这些数据

create or replace function useEasy(mid in nvarchar2)
  return number
  is
    FunctionResult number;
    SubNum number;
    CurrNum number;
  begin
    CurrNum := 1;
    select count(*) into SubNum from sys_menu m where m.parentid = mid;
    --CurrNum := SubNum + CurrNum;
    if SubNum > 0 then 
       CurrNum := CurrNum-1;
       FOR m1 IN (select m.id,m.parentid from sys_menu m where m.parentid = mid) LOOP
           
           CurrNum := CurrNum + useEasy(m1.id);
       
       end LOOP;
    
    end if;
    
    FunctionResult := CurrNum;
    return(FunctionResult);
end useEasy;

select m.id,m.parentid,m.menutext,m.menucode,m.menutext,useEasy(m.id) OccupyRow from sys_menu m 
where m.parentid = '2D14DFA8-8D9B-4034-A2CD-2099AD4A0A33'
order by m.menusort asc

 public class ExportUserPower
    {

        public ExportUserPower(string sheetName)
        {
            this.sheetName = sheetName;
        }

        public HSSFWorkbook ExcelWork { get; set; }


        public string WorkName { get; set; }
        private string sheetName { get; set; }
        public string SheetName
        {
            get
            {
                return sheetName;
            }
            set
            {
                value = sheetName;
            }
        }

        public List<HeadMenuTree> MenuList { get; set; }

        private string systemCode;
        public string SystemCode
        {
            get
            {
                return systemCode;
            }
            set
            {
                value = systemCode;
            }
        }



        /// <summary>
        /// 创建Sheet
        /// </summary>
        /// <param name="hwb"></param>
        /// <param name="sheetName"></param>
        /// <returns></returns>
        public HSSFSheet CreateSheet(HSSFWorkbook hwb, string sheetName)
        {
            //创建一个excel中的表格
            HSSFSheet sheet = (HSSFSheet)hwb.CreateSheet(sheetName);
            return sheet;
        }

        public ICell CreateCell(HSSFRow row, int num)
        {
            ICell cell = row.CreateCell(num);
            return cell;
        }


        public void ExportExcelWork()
        {
            //创建一个excel
            ExcelWork = new HSSFWorkbook();
            //创建一个excel中的表格
            HSSFSheet sheet = CreateSheet(ExcelWork, sheetName);
            CreateHeadMenu(sheet);
        }


        public void CreateHeadMenu(HSSFSheet sheet)
        {
            int _ColumnNum = 1;  //定义列
            int _RowNum = -1;    //定义行
            //HSSFRow headerrow = (HSSFRow)sheet.CreateRow(_RowNum);
            //headerrow.CreateCell(_ColumnNum).SetCellValue("用户");  //创建头部  列1  用户
            //TreeMenu sys_root = MenuList.Where(w => w.menucode == systemCode).FirstOrDefault();
            CreateAllMenuColl(sheet, MenuList, _RowNum, _ColumnNum);
            //sheet.AddMergedRegion(new NPOI.SS.Util.CellRangeAddress(0, 0, 0, 2));
        }

        public void CreateAllMenuColl(HSSFSheet sheet, List<HeadMenuTree> list, int row, int startColumn)
        {
            int f = 0;
            int thisRow = row + 1;
            IRow headerrow;
            if (sheet.LastRowNum < thisRow)
                headerrow = sheet.CreateRow(thisRow);
            else
                headerrow = sheet.GetRow(thisRow);
            if (headerrow == null)
                headerrow = sheet.CreateRow(thisRow);

            int thisColumn = startColumn;
            foreach (HeadMenuTree item in list)
            {
                //log4net.LogManager.GetLogger("OperationLogger").Error("thisColumn：" + thisColumn + "；thisRow：" + thisRow);

                ICell cell = headerrow.CreateCell(thisColumn);
                cell.CellStyle = CreateCellStyle();
                cell.SetCellValue(item.Name);

                if (thisColumn != (thisColumn + item.OccupyRow - 1))
                    sheet.AddMergedRegion(new CellRangeAddress(thisRow, thisRow, thisColumn, (thisColumn + item.OccupyRow) - 1));

                if (item.Children.Count > 0)
                    CreateAllMenuColl(sheet, item.Children, thisRow, thisColumn);

                thisColumn = (thisColumn + item.OccupyRow);

                f++;
            }

            thisColumn = 1;
            thisRow = 0;
        }

        public void FillData()
        {
            SystemMenuService service = new SystemMenuService();
            MenuList = service.GetAllHeadMenu("ZhanJiang");
        }


        public static void DataTree(string path, DataTable table, int treeIndex = 10000)
        {
            using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite))
            {
                IWorkbook workBook = new HSSFWorkbook();
                //现在使用的仍然是生成Excel2003的Excel文件，由于03对行数（65535）和列数（255）有限制，所以当数据超出范围后难免出错
                //ArgumentException: Invalid column index (256). Allowable column range for BIFF8 is (0..255) or ('A'..'IV') ...
                if (Path.GetExtension(path).Equals(".xlsx", System.StringComparison.OrdinalIgnoreCase))
                {
                    workBook = new XSSFWorkbook();
                }

                string sheetName = string.IsNullOrWhiteSpace(table.TableName) ? "Sheet1" : table.TableName;
                ISheet sheet = workBook.CreateSheet(sheetName);
                IRow row = null;
                int colNum = table.Columns.Count;
                if (treeIndex < table.Columns.Count || treeIndex > 0)
                {
                    colNum = treeIndex;
                }

                ICellStyle cellCenterStyle = GetCenter(workBook);

                int beginNum = 1;//排除列头，从1开始

                //处理表格列头
                row = sheet.CreateRow(beginNum - 1);
                for (int i = 0; i < table.Columns.Count; i++)
                {
                    string strVal = table.Columns[i].ColumnName;
                    ICell cell = row.CreateCell(i);
                    cell.SetCellValue(strVal);
                    cell.CellStyle = cellCenterStyle;
                    row.Height = 350;
                    sheet.AutoSizeColumn(i);
                }

                //处理数据内容
                for (int i = 0; i < table.Rows.Count; i++)
                {
                    row = sheet.CreateRow(beginNum + i);
                    row.Height = 250;
                    for (int j = 0; j < table.Columns.Count; j++)
                    {
                        string strVal = table.Rows[i][j].ToString();
                        ICell currCell = row.CreateCell(j);
                        currCell.SetCellValue(strVal);
                        currCell.CellStyle = cellCenterStyle;
                        sheet.SetColumnWidth(j, 256 * 15);
                    }
                }

                for (int i = 0; i < colNum; i++)
                {
                    List<int> lstColWidth = new List<int>();
                    string currVal = string.Empty;
                    string nextVal = string.Empty;
                    for (int j = beginNum; j <= sheet.LastRowNum; j++)
                    {
                        currVal = sheet.GetRow(j).Cells[i].StringCellValue;

                        int mk = j;
                        if (!string.IsNullOrWhiteSpace(currVal))//排除 空值，空值不做合并处理
                        {
                            for (int k = j + 1; k <= sheet.LastRowNum; k++)
                            {
                                nextVal = sheet.GetRow(k).Cells[i].StringCellValue;

                                if (currVal != nextVal)
                                {
                                    //因为k 累加所以导致当前值与下个值 不相同，所以记录 当前行数要 减去1
                                    mk = k - 1;
                                    break;
                                }
                                else if (k == sheet.LastRowNum) //边界值，处理最后一行，则提前Break 并记录当前 k
                                {
                                    mk = k;
                                    break;
                                }
                            }
                        }

                        if (mk != j)//排除 空值外，下个值的行数不等于当前行数，则需要合并
                        {
                            sheet.AddMergedRegion(new CellRangeAddress(j, mk, i, i));
                        }

                        //if (i == 0) //如果是第一列，则 垂直水平居中
                        {
                            sheet.GetRow(j).Cells[i].CellStyle = cellCenterStyle;
                        }
                        //跳到执行下一个不同数据的行
                        j = mk;

                        //记录列长度
                        lstColWidth.Add(DataLength(currVal));
                    }

                    //设置列宽
                    int maxWidth = lstColWidth.Max() * 200;
                    sheet.SetColumnWidth(i, maxWidth);
                }
                //固定列、行 滚动时不变
                sheet.CreateFreezePane(3, 1, 3, 1);

                //写入数据流
                workBook.Write(fs);
            }
        }

        private static ICellStyle GetCenter(IWorkbook workBook, short fontSize = 10)
        {
            ICellStyle cellStyle = workBook.CreateCellStyle();
            IFont font = workBook.CreateFont();
            font.FontName = "微软雅黑";
            font.FontHeightInPoints = fontSize;
            cellStyle.SetFont(font);
            cellStyle.VerticalAlignment = VerticalAlignment.Center;
            cellStyle.Alignment = HorizontalAlignment.Center;
            return cellStyle;
        }

        /// <summary>
        /// 获取字符串长度（中文按2个字节长度）
        /// </summary>
        /// <param name="stringWithEnglishAndChinese"></param>
        /// <returns></returns>
        private static int DataLength(string stringWithEnglishAndChinese)
        {
            int lng = 0;
            for (int i = 0; i < stringWithEnglishAndChinese.Length; i++)
            {
                byte[] b = System.Text.Encoding.Default.GetBytes(stringWithEnglishAndChinese.Substring(i, 1));
                if (b.Length > 1)
                    lng += 2;
                else
                    lng += 1;
            }
            return lng;
        }

        public ICellStyle CreateCellStyle()
        {
            ICellStyle cellStyle = ExcelWork.CreateCellStyle();
            cellStyle.BorderBottom = BorderStyle.Thin;
            cellStyle.BorderLeft = BorderStyle.Thin;
            cellStyle.BorderRight = BorderStyle.Thin;
            cellStyle.BorderTop = BorderStyle.Thin;
            return cellStyle;
        }











    }