C#內存表數據透視表生成

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;

namespace GT
{
    /// <summary>
    /// 內存表透視表生成器 2020.3.10
    /// 調用方法new PivotTableGenerator(dt, "dq,xz,cw","fl","sl", "dq=地區,xz=小組,cw=財務").CreatePivotTable();
    /// </summary>
    public class PivotTableGenerator
    {

        private DataTable _source;
        private DataTable _result;

        string[] _fields;
        string _valueFileld;
        string _pivotField;
        private string _fieldRenameString;

        /// <summary>
        /// 內存表透視表生成器 構造方式
        /// 調用方法new PivotTableGenerator(dt, "dq,xz,cw","fl","sl", "dq=地區,xz=小組,cw=財務").CreatePivotTable();
        /// </summary>
        /// <param name="source"></param>
        /// <param name="fields">如</param>
        /// <param name="pivotField"></param>
        /// <param name="valueField"></param>
        /// <param name="fieldRenameString"></param>
        public PivotTableGenerator(DataTable source, string fields, string pivotField, string valueField, string fieldRenameString)
        {
            if (null == source || string.IsNullOrEmpty(fields) || string.IsNullOrEmpty(pivotField) || string.IsNullOrEmpty(valueField))
            {
                throw new Exception(" PivotTableGenerator 初始化錯誤");
            }

            _source = source;
            _fields = fields.Split(',');
            _valueFileld = valueField;
            _pivotField = pivotField;
            _fieldRenameString = fieldRenameString;
        }

        public DataTable CreatePivotTable()
        {
            _result = new DataTable();

            //fields
            DataTable dt = new DataView(_source).ToTable(true, _fields);
            for (int i = 0; i < dt.Columns.Count; i++)
            {
                DataColumn col = new DataColumn(dt.Columns[i].ColumnName, dt.Columns[i].DataType);
                _result.Columns.Add(col);
            }

            foreach (DataRow dataRow in dt.Rows)
            {
                DataRow dr = _result.NewRow();
                foreach (DataColumn dataColumn in dt.Columns)
                {
                    dr[dataColumn.ColumnName] = dataRow[dataColumn.ColumnName];
                }
                _result.Rows.Add(dr);
            }

            if (0 == _source.Rows.Count)
                return _result;

            //pivot
            List<string> pivotColumns = new List<string>();
            Type valueType = _source.Columns[_valueFileld].DataType;
            dt = new DataView(_source).ToTable(true, _pivotField);
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                string pivotFieldName = dt.Rows[i][0].ToString();
                DataColumn col = new DataColumn(pivotFieldName, valueType);
                _result.Columns.Add(col);
                pivotColumns.Add(pivotFieldName);
            }

            //fild data  暫時設爲無重複數據
            List<string> filter0;

            foreach (DataRow dataRow in _result.Rows)
            {
                filter0 = new List<string>();
                foreach (var item in _fields)
                    filter0.Add(string.Format("{0} = '{1}'", item, dataRow[item].ToString()));

                foreach (string pivotFieldValue in pivotColumns)
                {
                    List<string> filter1 = new List<string>(filter0);
                    filter1.Add(string.Format("{0} = '{1}'", _pivotField, pivotFieldValue));
                    DataRow[] drSources = _source.Select(string.Join(" and ", filter1));
                    if (null != drSources && drSources.Length > 0)
                        dataRow[pivotFieldValue] = drSources[0][_valueFileld];
                }

            }

            if (!string.IsNullOrEmpty(_fieldRenameString))
                this.ChangeFiledName();

            return _result;
        }



        /// <summary>
        /// 更改內存表字段名稱，忽略大小寫
        /// </summary>
        private void ChangeFiledName()
        {
            if (!string.IsNullOrEmpty(_fieldRenameString))
            {
                 
                string[]  arr1 = _fieldRenameString.Split(',');
                for (int i = 0; i < arr1.Length; i++)
                {
                    arr1[i] = arr1[i].Trim();
                    if (arr1[i].Length < 1)
                        continue;

                    string[] arr2 = arr1[i].Split('=');
                    if (arr2.Length < 2)
                        continue;

                    arr2[0] = arr2[0].Trim();
                    arr2[1] = arr2[1].Trim();

                    if (arr2[0].Length < 1 || arr2[1].Length < 1)
                        continue;

                    foreach (DataColumn column in _result.Columns)
                    {
                        if (column.ColumnName.ToLower().Equals(arr2[0].ToLower()))
                            column.ColumnName = arr2[1];
                    }
                }
            }

        }

    }
}