c# 对DataTable各种常用操作的源代码DataTableHelper

本是古典何须时尚 2022-04-11 06:26 552阅读 0赞

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Text;  
using System.Data;  
using System.Collections;  
using System.ComponentModel;  
namespace Soft.Lib  
\{  
/// <summary>  
/// DataTable操作  
/// </summary>  
public abstract class DataTableHelper  
\{  
/// <summary>  
/// 将DataTable按起始位置和移动及移动方向进行移动并返回新的DataTable  
/// </summary>  
/// <param name="dt">要移动的DataTable</param>  
/// <param name="StartRow">要移动的行（索引从1开始）</param>  
/// <param name="MoveCount">要移动的行数</param>  
/// <param name="MoveUp">是否上移（true为上移false为下移）</param>  
/// <returns>将移动完成后的DataTable返回，如果移动有误的话将返回原Table</returns>  
static public DataTable GetNewTable(DataTable dt, int StartRow, int MoveCount, bool MoveUp)  
\{  
\#region 将DataTable按起始位置和移动及移动方向进行移动并返回新的DataTable  
  
DataRow dr = dt.NewRow();  
dr.ItemArray = dt.Rows\[StartRow - 1\].ItemArray;  
int RowCount = dt.Rows.Count;  
if (StartRow > RowCount)//移动的行在行数外面  
return dt;  
if (MoveUp)//上移  
\{  
if (StartRow - MoveCount <= 0) \{ \}  
else  
\{  
for (int i = 0; i < MoveCount; i++)  
dt.Rows\[StartRow - i - 1\].ItemArray = dt.Rows\[StartRow - i - 2\].ItemArray;  
dt.Rows\[StartRow - MoveCount - 1\].ItemArray = dr.ItemArray;  
\}  
\}  
else//下移  
\{  
if (StartRow + MoveCount > RowCount) \{ \}  
else  
\{  
for (int i = 0; i < MoveCount; i++)  
dt.Rows\[StartRow + i - 1\].ItemArray = dt.Rows\[StartRow + i\].ItemArray;  
dt.Rows\[StartRow + MoveCount - 1\].ItemArray = dr.ItemArray;  
\}  
\}  
return dt;  
\#endregion  
\}  
  
/// <summary>  
/// 根据条件过滤表  
/// </summary>  
/// <param name="dt">未过滤之前的表</param>  
/// <param name="filter">过滤条件</param>  
/// <returns>返回过滤后的表</returns>  
static public DataTable GetNewTable(DataTable dt, string filter)  
\{  
\#region 根据条件过滤表  
DataTable newTable = dt.Clone();  
DataRow\[\] drs = dt.Select(filter);  
foreach (DataRow dr in drs)  
\{  
object\[\] arr = dr.ItemArray;  
DataRow newrow = newTable.NewRow();  
for (int i = 0; i < arr.Length; i++)  
newrow\[i\] = arr\[i\];  
newTable.Rows.Add(newrow);  
\}  
return newTable;  
\#endregion  
\}  
// <summary>  
/// 根据条件过滤表  
/// </summary>  
/// <param name="dt">未过滤之前的表</param>  
/// <param name="filter">过滤条件</param>  
/// <returns>返回过滤后的表</returns>  
static public DataTable GetNewTable(DataTable dt, string filter, string sort)  
\{  
\#region 根据条件过滤表  
DataTable newTable = dt.Clone();  
DataRow\[\] drs = dt.Select(filter, sort);  
foreach (DataRow dr in drs)  
\{  
object\[\] arr = dr.ItemArray;  
DataRow newrow = newTable.NewRow();  
for (int i = 0; i < arr.Length; i++)  
newrow\[i\] = arr\[i\];  
newTable.Rows.Add(newrow);  
\}  
return newTable;  
\#endregion  
\}  
/// <summary>  
/// 根据条件过滤表  
/// </summary>  
/// <param name="dt">未过滤之前的表</param>  
/// <param name="filter">过滤条件</param>  
/// <returns>返回过滤后的表</returns>  
static public DataTable GetNewTableByDataView(DataTable dt, string filter)  
\{  
\#region 根据条件过滤表  
DataView dv = new DataView(dt);  
dv.RowFilter = filter;  
return dv.Table;  
\#endregion  
\}  
/// <summary>  
/// 返回两个表的关联数据，关联后的表中只包含第一个表的字段和第二个表需要的字段  
/// </summary>  
/// <param name="FirstTable">第一个表（左表）</param>  
/// <param name="SecondTable">第二个表（右表）</param>  
/// <param name="FJC">第一个表要与第二个表关联的字段</param>  
/// <param name="SJC">第二个表要与第一个表关联的字段</param>  
/// <param name="SJCNeed">第二个表中需要保留的字段</param>  
/// <param name="IsLeftOuter">是否是左外连接，否则为内连接</param>  
/// <returns></returns>  
private static DataTable LeftOuterOrJoin(DataTable FirstTable, DataTable SecondTable, DataColumn\[\] FJC, DataColumn\[\] SJC, DataColumn\[\] SJCNeed, bool IsLeftOuter)  
\{  
  
//创建一个新的DataTable  
  
DataTable table = new DataTable("LJoin");  
// Use a DataSet to leverage DataRelation  
using (DataSet ds = new DataSet())  
\{  
  
//把DataTable Copy到DataSet中  
//ds.Tables.AddRange(new DataTable\[\]\{First.Copy(),Second.Copy()\});  
DataTable First = FirstTable.Copy();  
DataTable Second = SecondTable.Copy();  
First.TableName = "FirstTable";  
Second.TableName = "SecondTable";  
  
for (int i = 0; i < Second.Columns.Count; i++)//删除第二个表中不需要的字段  
\{  
bool Conten = false;  
for (int j = 0; j < SJC.Length; j++)  
\{  
if (SJC\[j\].ColumnName.ToUpper().Trim() == Second.Columns\[i\].ColumnName.ToUpper().Trim())  
\{  
Conten = true;  
break;  
\}  
\}  
if (!Conten)  
\{  
for (int j = 0; j < SJCNeed.Length; j++)  
\{  
if (SJCNeed\[j\].ColumnName.ToUpper().Trim() == Second.Columns\[i\].ColumnName.ToUpper().Trim())  
\{  
Conten = true;  
break;  
\}  
\}  
\}  
if (!Conten)  
\{  
Second.Columns.RemoveAt(i);  
i--;  
\}  
\}  
ds.Tables.AddRange(new DataTable\[\] \{ First, Second \});  
DataColumn\[\] parentcolumns = new DataColumn\[FJC.Length\];  
for (int i = 0; i < parentcolumns.Length; i++)  
\{  
parentcolumns\[i\] = ds.Tables\[0\].Columns\[FJC\[i\].ColumnName\];  
\}  
  
DataColumn\[\] childcolumns = new DataColumn\[SJC.Length\];  
for (int i = 0; i < childcolumns.Length; i++)  
\{  
childcolumns\[i\] = ds.Tables\[1\].Columns\[SJC\[i\].ColumnName\];  
\}  
  
//创建关联  
DataRelation r = new DataRelation(string.Empty, parentcolumns, childcolumns, false);  
ds.Relations.Add(r);  
//为关联表创建列  
for (int i = 0; i < First.Columns.Count; i++)  
\{  
table.Columns.Add(First.Columns\[i\].ColumnName, First.Columns\[i\].DataType);  
\}  
  
for (int i = 0; i < Second.Columns.Count; i++)  
\{  
//看看有没有重复的列，如果有在第二个DataTable的Column的列明后加\_Second  
if (!table.Columns.Contains(Second.Columns\[i\].ColumnName))  
\{  
table.Columns.Add(Second.Columns\[i\].ColumnName, Second.Columns\[i\].DataType);  
\}  
else  
\{  
table.Columns.Add(Second.Columns\[i\].ColumnName + "\_Second", Second.Columns\[i\].DataType);  
\}  
\}  
table.BeginLoadData();  
foreach (DataRow firstrow in ds.Tables\[0\].Rows)  
\{  
//得到行的数据  
DataRow\[\] childrows = firstrow.GetChildRows(r);  
if (childrows != null && childrows.Length > 0)  
\{  
object\[\] parentarray = firstrow.ItemArray;  
foreach (DataRow secondrow in childrows)  
\{  
object\[\] secondarray = secondrow.ItemArray;  
object\[\] joinarray = new object\[parentarray.Length + secondarray.Length\];  
Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);  
Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);  
table.LoadDataRow(joinarray, true);  
\}  
\}  
else  
\{  
if (IsLeftOuter)  
\{  
object\[\] parentarray = firstrow.ItemArray;  
DataRow secondrow = Second.NewRow();  
\{  
object\[\] secondarray = secondrow.ItemArray;  
object\[\] joinarray = new object\[parentarray.Length + secondarray.Length\];  
Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);  
Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);  
table.LoadDataRow(joinarray, true);  
\}  
\}  
\}  
\}  
table.EndLoadData();  
\}  
for (int i = 0; i < table.Columns.Count; i++)  
\{  
if (table.Columns\[i\].ColumnName.EndsWith("\_Second"))  
\{  
table.Columns.RemoveAt(i);  
i--;  
\}  
\}  
return table;  
  
\}  
/// <summary>  
/// 返回两个表的关联数据  
/// </summary>  
/// <param name="FirstTable">第一个表（左表）</param>  
/// <param name="SecondTable">第二个表（右表）</param>  
/// <param name="FJC">第一个表要与第二个表关联的字段</param>  
/// <param name="SJC">第二个表要与第一个表关联的字段</param>  
/// <param name="IsLeftOuter">是否是左外连接，否则为内连接</param>  
/// <returns></returns>  
private static DataTable LeftOuterOrJoin(DataTable FirstTable, DataTable SecondTable, DataColumn\[\] FJC, DataColumn\[\] SJC, bool IsLeftOuter)  
\{  
  
//创建一个新的DataTable  
  
DataTable table = new DataTable("Join");  
// Use a DataSet to leverage DataRelation  
using (DataSet ds = new DataSet())  
\{  
  
//把DataTable Copy到DataSet中  
//ds.Tables.AddRange(new DataTable\[\]\{First.Copy(),Second.Copy()\});  
  
DataTable First = FirstTable.Copy();  
DataTable Second = SecondTable.Copy();  
First.TableName = "FirstTable";  
Second.TableName = "SecondTable";  
ds.Tables.AddRange(new DataTable\[\] \{ First, Second \});  
DataColumn\[\] parentcolumns = new DataColumn\[FJC.Length\];  
for (int i = 0; i < parentcolumns.Length; i++)  
\{  
parentcolumns\[i\] = ds.Tables\[0\].Columns\[FJC\[i\].ColumnName\];  
\}  
  
DataColumn\[\] childcolumns = new DataColumn\[SJC.Length\];  
for (int i = 0; i < childcolumns.Length; i++)  
\{  
childcolumns\[i\] = ds.Tables\[1\].Columns\[SJC\[i\].ColumnName\];  
\}  
  
//创建关联  
DataRelation r = new DataRelation(string.Empty, parentcolumns, childcolumns, false);  
ds.Relations.Add(r);  
//为关联表创建列  
for (int i = 0; i < First.Columns.Count; i++)  
\{  
table.Columns.Add(First.Columns\[i\].ColumnName, First.Columns\[i\].DataType);  
\}  
  
for (int i = 0; i < Second.Columns.Count; i++)  
\{  
//看看有没有重复的列，如果有在第二个DataTable的Column的列明后加\_Second  
if (!table.Columns.Contains(Second.Columns\[i\].ColumnName))  
\{  
table.Columns.Add(Second.Columns\[i\].ColumnName, Second.Columns\[i\].DataType);  
\}  
else  
\{  
table.Columns.Add(Second.Columns\[i\].ColumnName + "\_Second", Second.Columns\[i\].DataType);  
\}  
\}  
table.BeginLoadData();  
foreach (DataRow firstrow in ds.Tables\[0\].Rows)  
\{  
//得到行的数据  
DataRow\[\] childrows = firstrow.GetChildRows(r);  
if (childrows != null && childrows.Length > 0)  
\{  
object\[\] parentarray = firstrow.ItemArray;  
foreach (DataRow secondrow in childrows)  
\{  
object\[\] secondarray = secondrow.ItemArray;  
object\[\] joinarray = new object\[parentarray.Length + secondarray.Length\];  
Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);  
Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);  
table.LoadDataRow(joinarray, true);  
\}  
\}  
else if (IsLeftOuter)  
\{  
object\[\] parentarray = firstrow.ItemArray;  
DataRow secondrow = Second.NewRow();  
\{  
object\[\] secondarray = secondrow.ItemArray;  
object\[\] joinarray = new object\[parentarray.Length + secondarray.Length\];  
Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);  
Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);  
table.LoadDataRow(joinarray, true);  
\}  
\}  
\}  
table.EndLoadData();  
\}  
return table;  
  
\}  
/// <summary>  
///  
/// </summary>  
/// <param name="FirstTable"></param>  
/// <param name="SecondTable"></param>  
/// <param name="FJC"></param>  
/// <param name="SJC"></param>  
/// <returns></returns>  
public static DataTable Join(DataTable FirstTable, DataTable SecondTable, DataColumn\[\] FJC, DataColumn\[\] SJC)  
\{  
return LeftOuterOrJoin(FirstTable, SecondTable, FJC, SJC, false);  
\}  
public static DataTable Join(DataTable First, DataTable Second, DataColumn FJC, DataColumn SJC)  
\{  
return Join(First, Second, new DataColumn\[\] \{ FJC \}, new DataColumn\[\] \{ SJC \});  
\}  
public static DataTable Join(DataTable First, DataTable Second, string FJC, string SJC)  
\{  
return Join(First, Second, new DataColumn\[\] \{ First.Columns\[FJC\] \}, new DataColumn\[\] \{ Second.Columns\[SJC\] \});  
\}  
public static DataTable Join(DataTable First, DataTable Second, string \[\]FJC, string \[\]SJC)  
\{  
if (First == null || Second == null || FJC == null || SJC == null )  
\{  
return null;  
\}  
DataColumn\[\] FJColumns = new DataColumn\[FJC.Length\];  
for (int i = 0; i < FJC.Length; i++)  
\{  
FJColumns\[i\] = First.Columns\[FJC\[i\].Trim()\];  
\}  
DataColumn\[\] SJColumns = new DataColumn\[SJC.Length\];  
for (int i = 0; i < SJC.Length; i++)  
\{  
SJColumns\[i\] = Second.Columns\[SJC\[i\].Trim()\];  
\}  
return Join(First, Second, FJColumns, SJColumns);  
\}  
  
  
  
public static DataTable Join(DataTable FirstTable, DataTable SecondTable, DataColumn\[\] FJC, DataColumn\[\] SJC, DataColumn\[\] SJCNeed)  
\{  
return LeftOuterOrJoin(FirstTable, SecondTable, FJC, SJC, SJCNeed, false );  
\}  
public static DataTable Join(DataTable First, DataTable Second, string FJC, string SJC, params string\[\] SecondNeedS)  
\{  
if (First == null || Second == null || FJC == null || SJC == null || SecondNeedS == null)  
\{  
return null;  
\}  
DataColumn\[\] SecondNeedScolumns = new DataColumn\[SecondNeedS.Length\];  
for (int i = 0; i < SecondNeedS.Length; i++)  
\{  
SecondNeedScolumns\[i\] = Second.Columns\[SecondNeedS\[i\].Trim()\];  
\}  
return Join(First, Second, new DataColumn\[\] \{ First.Columns\[FJC\] \}, new DataColumn\[\] \{ Second.Columns\[SJC\] \}, SecondNeedScolumns);  
\}  
public static DataTable Join(DataTable First, DataTable Second, string\[\] FJC, string\[\] SJC ,string\[\] SecondNeedS)  
\{  
if (First == null || Second == null || FJC == null || SJC == null||SecondNeedS==null )  
\{  
return null;  
\}  
DataColumn\[\] FJColumns = new DataColumn\[FJC.Length\];  
for (int i = 0; i < FJC.Length; i++)  
\{  
FJColumns\[i\] = First.Columns\[FJC\[i\].Trim()\];  
\}  
DataColumn\[\] SJColumns = new DataColumn\[SJC.Length\];  
for (int i = 0; i < SJC.Length; i++)  
\{  
SJColumns\[i\] = Second.Columns\[SJC\[i\].Trim()\];  
\}  
DataColumn\[\] SecondNeedScolumns = new DataColumn\[SecondNeedS.Length\];  
for (int i = 0; i < SecondNeedS.Length; i++)  
\{  
SecondNeedScolumns\[i\] = Second.Columns\[SecondNeedS\[i\].Trim()\];  
\}  
return Join(First, Second, FJColumns, SJColumns, SecondNeedScolumns);  
\}  
  
  
public static DataTable LeftOuterJoin(DataTable FirstTable, DataTable SecondTable, DataColumn\[\] FJC, DataColumn\[\] SJC)  
\{  
return LeftOuterOrJoin(FirstTable, SecondTable, FJC, SJC, true );  
\}  
public static DataTable LeftOuterJoin(DataTable First, DataTable Second, string FJC, string SJC)  
\{  
return LeftOuterJoin(First, Second, new DataColumn\[\] \{ First.Columns\[FJC\] \}, new DataColumn\[\] \{ Second.Columns\[SJC\] \});  
\}  
public static DataTable LeftOuterJoin(DataTable First, DataTable Second, string\[\] FJC, string\[\] SJC)  
\{  
if (First == null || Second == null || FJC == null || SJC == null)  
\{  
return null;  
\}  
DataColumn\[\] FJColumns = new DataColumn\[FJC.Length\];  
for (int i = 0; i < FJC.Length; i++)  
\{  
FJColumns\[i\] = First.Columns\[FJC\[i\].Trim()\];  
\}  
DataColumn\[\] SJColumns = new DataColumn\[SJC.Length\];  
for (int i = 0; i < SJC.Length; i++)  
\{  
SJColumns\[i\] = Second.Columns\[SJC\[i\].Trim()\];  
\}  
return LeftOuterJoin(First, Second, FJColumns, SJColumns);  
\}  
  
  
public static DataTable LeftOuterJoin(DataTable FirstTable, DataTable SecondTable, DataColumn\[\] FJC, DataColumn\[\] SJC, DataColumn\[\] SJCNeed)  
\{  
return LeftOuterOrJoin(FirstTable, SecondTable, FJC, SJC, SJCNeed, true);  
\}  
public static DataTable LeftOuterJoin(DataTable First, DataTable Second, string FJC, string SJC, params string\[\] SecondNeedS)  
\{  
if (First == null || Second == null || FJC == null || SJC == null || SecondNeedS == null)  
\{  
return null;  
\}  
DataColumn\[\] SecondNeedScolumns = new DataColumn\[SecondNeedS.Length\];  
for (int i = 0; i < SecondNeedS.Length; i++)  
\{  
SecondNeedScolumns\[i\] = Second.Columns\[SecondNeedS\[i\].Trim()\];  
\}  
return LeftOuterJoin(First, Second, new DataColumn\[\] \{ First.Columns\[FJC\] \}, new DataColumn\[\] \{ Second.Columns\[SJC\] \}, SecondNeedScolumns);  
\}  
public static DataTable LeftOuterJoin(DataTable First, DataTable Second, string\[\] FJC, string\[\] SJC, string\[\] SecondNeedS)  
\{  
if (First == null || Second == null || FJC == null || SJC == null || SecondNeedS == null)  
\{  
return null;  
\}  
DataColumn\[\] FJColumns = new DataColumn\[FJC.Length\];  
for (int i = 0; i < FJC.Length; i++)  
\{  
FJColumns\[i\] = First.Columns\[FJC\[i\].Trim()\];  
\}  
DataColumn\[\] SJColumns = new DataColumn\[SJC.Length\];  
for (int i = 0; i < SJC.Length; i++)  
\{  
SJColumns\[i\] = Second.Columns\[SJC\[i\].Trim()\];  
\}  
DataColumn\[\] SecondNeedScolumns = new DataColumn\[SecondNeedS.Length\];  
for (int i = 0; i < SecondNeedS.Length; i++)  
\{  
SecondNeedScolumns\[i\] = Second.Columns\[SecondNeedS\[i\].Trim()\];  
\}  
return LeftOuterJoin(First, Second, FJColumns, SJColumns, SecondNeedScolumns);  
\}  
  
/// <summary>  
/// 将Datatable封装成泛型  
/// </summary>  
/// <param name="table"></param>  
/// <returns></returns>  
public static IEnumerable<DataRow> TableToIEnumerable(DataTable table)  
\{  
return new LinqList<DataRow>(table.Rows);  
\}  
private static bool RowEqual(DataRow rowA, DataRow rowB, DataColumnCollection columns)  
\{  
// bool result = true;  
for (int i = 0; i < columns.Count; i++)  
\{  
//result &= ColumnEqual(rowA\[columns\[i\].ColumnName\], rowB\[columns\[i\].ColumnName\]);  
if (!ColumnEqual(rowA\[columns\[i\].ColumnName\], rowB\[columns\[i\].ColumnName\]))  
\{  
return false;  
\}  
\}  
return true ;  
\}  
  
private static bool ColumnEqual(object objectA, object objectB)  
\{  
if (objectA == DBNull.Value && objectB == DBNull.Value)  
\{  
return true;  
\}  
if (objectA == DBNull.Value || objectB == DBNull.Value)  
\{  
return false;  
\}  
return (objectA.Equals(objectB));  
\}  
  
  
/// <summary>  
/// 按照fieldName从sourceTable中选择出不重复的行，  
/// 相当于select distinct fieldName1,fieldName2,fieldNamen from sourceTable  
/// </summary>  
/// <param name="tableName">表名</param>  
/// <param name="sourceTable">源DataTable</param>  
/// <param name="fieldNames">列名数组</param>  
/// <returns>一个新的不含重复行的DataTable，列只包括fieldNames中指明的列</returns>  
public static DataTable SelectDistinct(string tableName, DataTable sourceTable, string\[\] fieldNames)  
\{  
DataTable dt = new DataTable(tableName);  
object\[\] values = new object\[fieldNames.Length\];  
string fields = "";  
for (int i = 0; i < fieldNames.Length; i++)  
\{  
dt.Columns.Add(fieldNames\[i\], sourceTable.Columns\[fieldNames\[i\]\].DataType);  
fields += fieldNames\[i\] + ",";  
\}  
fields = fields.Remove(fields.Length - 1, 1);  
DataRow lastRow = null;  
foreach (DataRow dr in sourceTable.Select("", fields))  
\{  
if (lastRow == null || !(RowEqual(lastRow, dr, dt.Columns)))  
\{  
lastRow = dr;  
for (int i = 0; i < fieldNames.Length; i++)  
\{  
values\[i\] = dr\[fieldNames\[i\]\];  
\}  
dt.Rows.Add(values);  
\}  
\}  
return dt;  
\}  
/// <summary>  
/// 按照fieldName从sourceTable中选择出不重复的行，  
/// 相当于select distinct fieldName1,fieldName2,fieldNamen from sourceTable  
/// </summary>  
/// <param name="sourceTable">源DataTable</param>  
/// <param name="fieldNames">列名数组</param>  
/// <returns>一个新的不含重复行的DataTable，列只包括fieldNames中指明的列</returns>  
public static DataTable SelectDistinct( DataTable sourceTable, string\[\] fieldNames)  
\{  
DataTable dt = new DataTable();  
object\[\] values = new object\[fieldNames.Length\];  
string fields = "";  
for (int i = 0; i < fieldNames.Length; i++)  
\{  
dt.Columns.Add(fieldNames\[i\], sourceTable.Columns\[fieldNames\[i\]\].DataType);  
fields += fieldNames\[i\] + ",";  
\}  
fields = fields.Remove(fields.Length - 1, 1);  
DataRow lastRow = null;  
foreach (DataRow dr in sourceTable.Select("", fields))  
\{  
if (lastRow == null || !(RowEqual(lastRow, dr, dt.Columns)))  
\{  
lastRow = dr;  
for (int i = 0; i < fieldNames.Length; i++)  
\{  
values\[i\] = dr\[fieldNames\[i\]\];  
\}  
dt.Rows.Add(values);  
\}  
\}  
return dt;  
\}  
  
/// <summary>  
/// 根据表的三个个字段 去掉重复行 2011-12-12  
/// </summary>  
/// <param name="dt"></param>  
/// <param name="filed1"></param>  
/// <param name="filed2"></param>  
/// <param name="filed3"></param>  
static public DataTable GetTable(DataTable dt, string filed1, string filed2, string filed3)  
\{  
DataTable newdt = new DataTable();  
newdt = dt.Clone();  
bool Have = false;  
if (dt.Rows.Count > 0)  
\{  
for (int i = 0; i < dt.Rows.Count; i++)  
\{  
Have = false;  
for (int j = i + 1; j < dt.Rows.Count; j++)  
\{  
if (dt.Rows\[i\]\[filed1\].ToString().Trim() == dt.Rows\[j\]\[filed1\].ToString().Trim() && dt.Rows\[i\]\[filed2\].ToString().Trim() == dt.Rows\[j\]\[filed2\].ToString().Trim() && dt.Rows\[i\]\[filed3\].ToString().Trim() == dt.Rows\[j\]\[filed3\].ToString().Trim())  
\{  
Have = true;  
break;  
\}  
\}  
if (!Have)  
\{  
newdt.ImportRow(dt.Rows\[i\]);  
\}  
\}  
  
\}  
return newdt;  
\}  
  
  
  
\}  
public class LinqList<T> : IEnumerable<T>, IEnumerable  
\{  
IEnumerable items;  
internal LinqList(IEnumerable items)  
\{  
this.items = items;  
\}  
\#region IEnumerable<DataRow> Members  
IEnumerator<T> IEnumerable<T>.GetEnumerator()  
\{  
foreach (T item in items) yield return item;  
\}  
IEnumerator IEnumerable.GetEnumerator()  
\{  
IEnumerable<T> ie = this;  
return ie.GetEnumerator();  
\}  
\#endregion  
  
\}  
  
public static class Projecttable  
\{  
public static DataTable CopyToDataTable<T>(this IEnumerable<T> array)  
\{  
var ret = new DataTable();  
foreach (PropertyDescriptor dp in TypeDescriptor.GetProperties(typeof(T)))  
// if (!dp.IsReadOnly)  
ret.Columns.Add(dp.Name, dp.PropertyType);  
foreach (T item in array)  
\{  
var Row = ret.NewRow();  
foreach (PropertyDescriptor dp in TypeDescriptor.GetProperties(typeof(T)))  
// if (!dp.IsReadOnly)  
Row\[dp.Name\] = dp.GetValue(item);  
ret.Rows.Add(Row);  
\}  
return ret;  
\}  
\}  
\}