借鉴一下对比算法

1         /// <summary>
        /// 比较两个DataTable数据（结构相同,字段名不同）
        /// </summary>
        /// <param name="dtDest">来自数据库的DataTable</param>
        /// <param name="dtSrc">来自文件的DataTable</param>
        /// <param name="dtRetAdd">新增数据（dt2中的数据）</param>
        /// <param name="dtRetDel">删除的数据（dt2中的数据）</param>
        /// <param name="srcKeyFields">源关键字段名</param>
        /// <param name="destKeyFields">目标关键字段名，与源关键字段名对应</param>
        public static void CompareDt(DataTable dtSrc, DataTable dtDest, out DataTable dtRetAdd, out DataTable dtRetDel, string srcKeyFields, string destKeyFields)
        {
            //源记录集与目标记录集有一个为null则退出
            if (dtSrc == null || dtDest == null)
            {
                dtRetDel = null;
                dtRetAdd = null;
                return;
            }
            //定义返回记录表
            dtRetDel = dtSrc.Clone();
            dtRetAdd = dtRetDel.Clone();
            //参照列为空则退出
            if (string.IsNullOrEmpty(srcKeyFields) || string.IsNullOrEmpty(destKeyFields))
                return;
            //获得参照列列表
            string[] srcFields = srcKeyFields.Split(‘,‘);//列名数组
            string[] destFields = destKeyFields.Split(‘,‘);//列名数组
            //参照列数目不一致则退出
            if (srcFields.Length != destFields.Length)
                return;
            //按参照列排序源表和目标表
            DataRow[] drSrc = dtSrc.Select("", srcKeyFields);
            DataRow[] drDest = dtDest.Select("", destKeyFields);
            //定义源表和目标表长度
            int iSrcCount = drSrc.Length;
            int iDestCount = drDest.Length;
            //源表为空则目标表全部加入删除队列并返回
            if (iSrcCount == 0)
            {
                foreach (DataRow row in drDest)
                {
                    dtRetDel.Rows.Add(row.ItemArray);
                }
                return;
            }
            //目标表为空则源表全部加入新增队列并返回
            if (iDestCount == 0)
            {
                foreach (DataRow row in drSrc)
                {
                    dtRetAdd.Rows.Add(row.ItemArray);
                }
                return;
            }
            //定义源表和目标表指针
            int iSrc = 0;
            int iDest = 0;
            //开始循环比对
            while (iSrc < iSrcCount && iDest < iDestCount)
            {
                //定义列比对结果
                int result = 0;
                object oSrc;
                object oDest;
                //循环比对列值
                for (int colIndex = 0; colIndex < srcFields.Length; colIndex++)
                {
                    //获得列值
                    oSrc = drSrc[iSrc][srcFields[colIndex]];
                    oDest = drDest[iDest][destFields[colIndex]];
                    //比较列值，不相等则退出循环
                    if (oSrc == DBNull.Value)
                    {
                        result = oDest == DBNull.Value ? 0 : -1;
                    }
                    else
                    {
                        result = oDest == DBNull.Value ? 1 : string.Compare(oSrc.ToString(), oDest.ToString(), false);
                    }
                    if (result != 0)
                        break;
                }
                //检查行比较结果
                switch (result)
                {
                    ////源表小则将源表本行加入新增队列，同时移动源表指针
                    case -1:
                        dtRetAdd.Rows.Add(drSrc[iSrc].ItemArray);
                        iSrc++;
                        break;
                    ////相同两表同时移动指针
                    case 0:
                        iSrc++;
                        iDest++;
                        break;
                    ////目标表小则将目标表本行加入删除队列，同时移动目标表指针
                    case 1:
                        dtRetDel.Rows.Add(drDest[iDest].ItemArray);
                        iDest++;
                        break;
                    default:
                        break;
                }
            }
            //源表到达最后一条，目标表未到达，则目标表剩余行全部加入删除队列
            if (iDest < iDestCount)
            {
                for (int index = iDest; index < iDestCount; index++)
                {
                    dtRetDel.Rows.Add(drDest[index].ItemArray);
                }
            }
            //目标表到达最后一条，源表未到达，则源表剩余行全部加入新增队列
            else if (iSrc < iSrcCount)
            {
                for (int index = iSrc; index < iSrcCount; index++)
                {
                    dtRetAdd.Rows.Add(drSrc[index].ItemArray);
                }
            }
121

       static void Main(string[] args)
        {
            DataTable dt1 = new DataTable();
            dt1.Columns.Add("a", System.Type.GetType("System.String"));
            DataRow dr = dt1.NewRow();
            dr["a"] = "1";
            DataRow dr1 = dt1.NewRow();
            dr1["a"] = "2";
            dt1.Rows.Add(dr1);
            DataRow dr2 = dt1.NewRow();
            dr2["a"] = "7";
            dt1.Rows.Add(dr2);
            DataRow dr3 = dt1.NewRow();
            dr3["a"] = "8";
            dt1.Rows.Add(dr3);
            DataRow dr4 = dt1.NewRow();
            dr4["a"] = "9";
            dt1.Rows.Add(dr4);

 
            DataTable dt2=new DataTable ();
            dt2.Columns.Add("b", System.Type.GetType("System.String"));
            DataRow dr5 = dt2.NewRow();
            dr5["b"] = "1";
            dt2.Rows.InsertAt(dr5, 0);
            DataRow dr6 = dt2.NewRow();
            dr6["b"] = "3";
            dt2.Rows.InsertAt(dr6, 0);
            DataRow dr7 = dt2.NewRow();
            dr7["b"] = "4";
            dt2.Rows.InsertAt(dr7, 0);
            DataRow dr8 = dt2.NewRow();
            dr8["b"] = "5";
            dt2.Rows.InsertAt(dr8, 0);
            DataRow dr9 = dt2.NewRow();
            dr9["b"] = "6";
            dt2.Rows.InsertAt(dr9, 0);
             DataTable dt3=new DataTable ();
             DataTable dt4=new DataTable ();
            CompareDt(dt1,dt2,out dt3,out dt4,"a","b");
        }