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/*

  已知 DataTable (first和 second) , 两个DataTable中都有一列 ID,并且值唯一

  要求:组织一个新的DataTable ,满足以下:
       如果 first 存在于 second 中则更新first的Name列为second的Name
       如果不存在则删除该行
       如果 second 的行不存在于first 就添加到 first中

*/
using System;
using System.Collections;
using System.Text;
using System.Data;

namespace ConsoleApplication1
{
    
class Program
    {
        
static void Main(string[] args)
        {
            Demo d 
= new Demo();
            d.Run();          
        }
    }

    
class Demo
    {
        DataTable first, second;       

        
public void Run()
        {
            
int i, j;
            first 
= new DataTable();
            first.Columns.Add(
"ID");
            first.Columns.Add(
"Name");
            DataRow dr;
            
for (i = 1; i < 100; i++)
            {
                dr 
= first.NewRow();
                dr[
0= i;
                dr[
1= i;
                first.Rows.Add(dr);
            }
            Console.Write(
"\n\nold first:\n");
            
foreach (DataRow outRow in first.Rows)
            {
                Console.Write(outRow[
0].ToString() + "  |  " + outRow[1].ToString() + "\n");
            }

            second 
= first.Clone();
            
this.AddToSecond(100001);
            
this.AddToSecond(220000);
            
this.AddToSecond(555555);
            
this.AddToSecond(100,00100);
            
this.AddToSecond(15000150);
            Console.Write(
"\n\nold second:\n");
            
foreach (DataRow outRow in second.Rows)
            {
                Console.Write(outRow[
0].ToString() + "  |  " + outRow[1].ToString() + "\n");
            }
            
int len1 = first.Rows.Count;
            
int len2 = second.Rows.Count;
            ArrayList DeleteRows 
= new ArrayList();
            ArrayList NewRows 
= new ArrayList();
            
for (i = 0, j = 0; i < len1 && j < len2; )
            {
                
string se = second.Rows[j][0].ToString();
                
string fi = first.Rows[i][0].ToString();
                
int compar = se.CompareTo(fi);
                
if (compar > 0//second > first
                {
                    DeleteRows.Add(i
++);//已经删除的
                }
                
else if (compar == 0)
                {
                    first.Rows[i][
1= second.Rows[j][1].ToString() + "(修改)";
                    i
++;
                    j
++;
                }
                
else
                {
                    NewRows.Add(j
++); //新加的
                }
            }
            
if (i < len1)
            {
                
//如果第一个没有遍历完,说明剩下的都是要删除的
                for (; i < len1; i++)
                {
                    DeleteRows.Add(i);
                }
            }
            
else if (j < len2)
            {
                
//如果第二个没有遍历完,说明剩下的都是要添加的
                for (; j < len2; j++)
                {
                    NewRows.Add(j);
                }
            }
            
//delete
            int[] DeleteArray = (int[])DeleteRows.ToArray(typeof(int));
            i 
= DeleteArray.Length - 1;
            
while (i > -1)
            {
                
//从后面开始删
                first.Rows.RemoveAt(DeleteArray[i]);
                i
--;
            }

            
//add new
            int[] NewArray = (int[])NewRows.ToArray(typeof(int));
            
for (i = 0; i < NewArray.Length; i++)
            {
                DataRow drNew 
= first.NewRow();
                drNew[
0= second.Rows[NewArray[i]][0];
                drNew[
1= second.Rows[NewArray[i]][1].ToString() + "(新增)";
                first.Rows.Add(drNew);
            }
            Console.Write(
"\n\nresult second:\n");
            
foreach (DataRow outRow in first.Rows)
            {
                Console.Write(outRow[
0].ToString() + "  |  " + outRow[1].ToString() + "\n");
            }
            Console.Read();
        }

        
private void AddToSecond(object text1, object text2)
        {
            DataRow dr24 
= second.NewRow();
            dr24[
0= text1;
            dr24[
1= text2;
            second.Rows.Add(dr24);
        }
    }
}

posted on 2007-06-12 23:53 colys 阅读(280) 评论(0)  编辑 收藏 引用 所属分类: C#.Net

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