快速找出DataTable中的重复行 【值得收藏】

 public override DataTable GetUserDataDTList(string excelPath)   
02.  
03.        {   
04.  
05.            excelPath = excelPath.Trim();   
06.  
07.            string filename = null;   
08.  
09.            try  
10.  
11.            {   
12.  
13.                filename = System.Configuration.ConfigurationSettings.AppSettings["filename"].ToString();   
14.  
15.            }   
16.  
17.            catch(Exception ex)   
18.  
19.            {   
20.  
21.                filename = null;   
22.  
23.                throw ex;   
24.  
25.            }   
26.  
27.            DataTable dt = new DataTable();   
28.  
29.            //DataSet ds = new DataSet();   
30.  
31.            if (string.IsNullOrEmpty(excelPath))   
32.  
33.            {   
34.  
35.                dt = null ;   
36.  
37.                //ds = null;   
38.  
39.            }   
40.  
41.            else  
42.  
43.            {   
44.  
45.                try  
46.  
47.                {   
48.  
49.                    string strConn = @"Provider = Microsoft.ACE.OLEDB.12.0;Data Source=" + excelPath + ";Extended Properties = 'Excel 12.0;HDR=Yes;IMEX=1;'";   
50.  
51.                    using(OleDbConnection oconn = new OleDbConnection(strConn))   
52.  
53.                    {   
54.  
55.                        OleDbCommand ocmd = null;   
56.  
57.                        oconn.Open();   
58.  
59.                        try  
60.  
61.                        {   
62.  
63.                            ocmd = new OleDbCommand("SELECT * FROM ["+filename+"$]", oconn);//在web.config中配置   
64.  
65.                            OleDbDataAdapter oda = new OleDbDataAdapter(ocmd);   
66.  
67.                            oda.Fill(dt);   
68.  
69.                        }   
70.  
71.                        catch(OleDbException oex)   
72.  
73.                        {   
74.  
75.                            dt = null;   
76.  
77.                            throw oex;   
78.  
79.                            //ds = null;   
80.  
81.                        }   
82.  
83.                        finally  
84.  
85.                        {   
86.  
87.                            oconn.Close();   
88.  
89.                            ocmd.Dispose();   
90.  
91.                        }   
92.  
93.                    }   
94.  
95.                }   
96.  
97.                catch(Exception ex)   
98.  
99.                {   
100.  
101.                    throw ex;   
102.  
103.                }   
104.  
105.            }   
106.  
107.            //return ds.Tables[0];   
108.  
109.            return dt;   
110.  
111.        }

说明：该方法需要一个参数用来获取Excel文件的路径，找到后放到一个DataTable中。  对于第二条，为了提高性能，我是这样实现的，每次遍历时只跟它后面的数据比较，因为它前面的数据已经跟它比较过了，没必要它再跟前面的数据比较

   /// <summary>   
02.  
03.        /// 查看Excel文件中重复的数据   
04.  
05.        /// 该方法只是比较编号和客户名称，其他字段没有比较   
06.  
07.        /// </summary>   
08.  
09.        /// <param name="excelPath">string：Excel文件路径</param>   
10.  
11.        /// <returns>ArrayList：重复行组成的动态数组</returns>   
12.  
13.        public static ArrayList arrCFData(string excelPath)   
14.  
15.        {   
16.  
17.            ArrayList arrUserData = new ArrayList();   
18.  
19.            excelPath=excelPath.Trim();   
20.  
21.            if (string.IsNullOrEmpty(excelPath))   
22.  
23.            {   
24.  
25.                arrUserData = null;   
26.  
27.            }   
28.  
29.            else  
30.  
31.            {   
32.  
33.                string ret = null;   
34.  
35.                DataTable dtCompInfo = null;   
36.  
37.                try    
38.  
39.                {   
40.  
41.                    dtCompInfo = DF.DBFactory.GetCompanyDAO().GetUserDataDTList(excelPath);   
42.  
43.                    if(dtCompInfo!=null&&dtCompInfo.Rows.Count>0)   
44.  
45.                    {   
46.  
47.                        int count = dtCompInfo.Rows.Count;   
48.  
49.                        int x, y;   
50.  
51.                        for (int i = 0; i < count;i++ )   
52.  
53.                        {   
54.  
55.                            for (int j = i + 1; j < count; j++)   
56.  
57.                            {   
58.  
59.                                if (dtCompInfo.Rows[i][0].ToString().Equals(dtCompInfo.Rows[j][0].ToString()) && dtCompInfo.Rows[i][3].ToString().Equals(dtCompInfo.Rows[j][3].ToString()))   
60.  
61.                                {   
62.  
63.                                    x = i + 2;   
64.  
65.                                    y = j + 2;   
66.  
67.                                    ret = string.Format("Excel数据中第{0}行和第{1}行数据重复",x, y);   
68.  
69.                                    arrUserData.Add(ret);   
70.  
71.                                    break;   
72.  
73.                                }   
74.  
75.                            }   
76.  
77.                            //arrUserData.Add(dtCompInfo.Rows[i][0].ToString() + "出来吧" + dtCompInfo.Rows[i][3].ToString());   
78.  
79.  
80.  
81.                        }   
82.  
83.                    }   
84.  
85.                }   
86.  
87.                catch(Exception ex)   
88.  
89.                {   
90.  
91.                    ExceptionManager.SaveException(ex, "Company.cs", ex.Message);   
92.  
93.                    arrUserData = null;   
94.  
95.                }   
96.  
97.                finally  
98.  
99.                {   
100.  
101.                    dtCompInfo = null;   
102.  
103.                }   
104.  
105.            }   
106.  
107.            return arrUserData;   
108.  
109.        }