¡ÒÃá¡éä¢: ¢éÍÁÙÅ·Õèà¡ÕèÂÇ¢éͧ¡Ñº¤ÍÁâ¾à¹¹µì·ÕèãªéÇѵ¶Ø System.Data ÍÒ¨àÊÕÂã¹â»Ãá¡ÃÁ»ÃÐÂØ¡µì·ÕèÊÃéÒ§º¹ Microsoft .NET Framework 2.0

• àÁ×èÍÁÕàÃÕ¡ÇÔ¸ÕAcceptChanges㹤ÅÒDataViewµÑǨѴ¡ÒÃÃÐàºÕ¹ÍÒ¨àÊÕÂËÒÂä»
• ÁÕ¡Òäӹdz¤èÒ㹤ÍÅÑÁ¹ì·ÕèÁÕ¹Ô¾¨¹ìÍÒ¨äÁèÊÒÁÒö»ÃѺ»Ãاä´éÍÂèÒ§¶Ù¡µéͧ
• àÁ×èÍÁÕàÃÕ¡ÇÔ¸ÕDataTable.Selectâ´Âãªé¤ÓÊÑè§ËÅÒ ÍÒ¨ä´éÃѺ¼ÅÅѾ¸ì·ÕèäÁè¶Ù¡µéͧ
• ´Ñª¹ÕÀÒÂ㹢ͧDataTableÇѵ¶ØÍÒ¨àÊÕÂËÒÂä» ¹Í¡¨Ò¡¹Õé ¤Ø³ä´éÃѺ¢éͤÇÒÁ¢éͼԴ¾ÅÒ´ '13'
• àÁ×è͵éͧ¡ÒôÓà¹Ô¹¡ÒüÊÒ¹à¡Ô´¢Öé¹ µÑǨѴ¡ÒÃÃÐàºÕ¹ÍÒ¨àÊÕ¶éÒá¶Çà»éÒËÁÒÂÍÂÙèã¹Ê¶Ò¹Ð·Õèá¡éä¢
• ´Ñª¹ÕÀÒÂ㹢ͧDataTableÇѵ¶ØÍÒ¨àÊÕÂËÒÂä» ¹Í¡¨Ò¡¹Õé ¤Ø³ä´éÃѺ¢éͤÇÒÁ¢éͼԴ¾ÅÒ´ '5'

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»Ñ­ËÒ·Õè 1: àÁ×èÍÁÕàÃÕ¡ÇÔ¸Õ AcceptChanges 㹤ÅÒ DataView µÑǨѴ¡ÒÃÃÐàºÕ¹ÍÒ¨àÊÕÂËÒÂ

1. ¤Ø³ÊÒÁÒöãªéÃËÑʴѧµèÍ仹Õéã¹á;ÅÔपѹ:

   using System;
   using System.ComponentModel;
   using System.Data;
   
   class Test {
       private static DataRow _dr = null;
       private static bool _accept = false;
       
       public static void Main()
       {
           try {
               DataSet ds = new DataSet();
               DataTable dt = ds.Tables.Add("Customers");
               DataColumn c = dt.Columns.Add("Id", typeof(int));
               dt.PrimaryKey = new DataColumn[] { c };
               dt.Columns.Add("Name", typeof(string));
               dt.Columns.Add("Age", typeof(int));
               
               dt.Rows.Add(new object[] { 1, "A", 10 });
               dt.Rows.Add(new object[] { 2, "B", 20 });
               dt.Rows.Add(new object[] { 3, "G", 30 });
               dt.Rows.Add(new object[] { 4, "H", 40 });
               dt.Rows.Add(new object[] { 5, "I", 50 });
   
               ds.AcceptChanges();
                           
               DataView dv = new DataView(dt);
               dv.Sort = "Name ASC";
                                       
               dv.ListChanged += new ListChangedEventHandler(OnListChanged);
                           
               _dr = dt.Rows[4];
               
               _accept = true;
               _dr["Name"] = "C";
               _accept = false;
                           
               _dr["Name"] = "D";
               _dr["Age"] = 55;            
                           
               Console.WriteLine(dv[2][1]);                        
           } catch (Exception exc) {
               Console.WriteLine(exc);
           }
       }
       
       public static void OnListChanged(object sender, ListChangedEventArgs args)
       {
           if (_dr != null && _accept) {
               _dr.AcceptChanges();
           }
       }
   }

2. ¤Ø³àÃÕ¡ãªéá;ÅÔपѹ

»Ñ­ËÒ·Õè 2: ÁÕ¡Òäӹdz¤èÒ㹤ÍÅÑÁ¹ì·ÕèÁÕ¹Ô¾¨¹ìÍÒ¨äÁèÊÒÁÒö»ÃѺ»Ãاä´éÍÂèÒ§¶Ù¡µéͧ

1. ¤Ø³ÊÒÁÒöãªéÃËÑʴѧµèÍ仹Õéã¹á;ÅÔपѹ:

   using System;
   using System.ComponentModel;
   using System.Data;
   
   class Test {
       public static void Main()
       {
           try {
               DataSet ds = new DataSet();
   
               DataTable dt1 = ds.Tables.Add("T1");
               dt1.Columns.Add("CustId", typeof(int));
               dt1.Columns.Add("CustName", typeof(string));
   
               DataTable dt2 = ds.Tables.Add("T2");
               dt2.Columns.Add("EmpId", typeof(int));
               DataColumn dcEmpName = dt2.Columns.Add("EmpName", typeof(string));
               DataColumn dcMgrName = dt2.Columns.Add("MgrName", typeof(string));
               DataColumn dcReports = dt2.Columns.Add("NumberOfReports", typeof(int));
               
               DataRelation rel1 = ds.Relations.Add("T1T2", dt1.Columns["CustId"], dt2.Columns["EmpId"], false);
               DataRelation rel2 = ds.Relations.Add("T2T2", dt2.Columns["EmpName"], dt2.Columns["MgrName"], false);
   
               dcEmpName.Expression = "Parent(T1T2).CustName";
               dcMgrName.Expression = "Parent(T1T2).CustName"; 
   
               //Each person is a manager to himself.
               dcReports.Expression = "Count(Child(T2T2).EmpName)"; 
   
               AddRow(dt1, 1, "N1");
               AddRow(dt1, 2, "N2");
               AddRow(dt1, 3, "N3");
   
               AddRow(dt2, 1);
               AddRow(dt2, 2);
               AddRow(dt2, 3);
   
               Console.WriteLine(ds.GetXml());
   
               dt1.Rows[0]["CustName"] = "N4";
   
               Console.WriteLine(ds.GetXml());
           } catch (Exception exc) {
               Console.WriteLine(exc);
           }
       }
   
       public static void AddRow(DataTable dt, params object[] objArr)
       {
           Console.WriteLine("Adding row to table {0}", dt.TableName);
           dt.Rows.Add(objArr);
       }
   }

2. ¤Ø³àÃÕ¡ãªéá;ÅÔपѹ

<NewDataSet>
 <T1>
   <CustId>1</CustId>
   <CustName>N4</CustName>
 </T1>
 <T1>
   <CustId>2</CustId>
   <CustName>N2</CustName>
 </T1>
 <T1>
   <CustId>3</CustId>
   <CustName>N3</CustName>
 </T1>
 <T2>
   <EmpId>1</EmpId>
   <EmpName>N4</EmpName>
   <MgrName>N4</MgrName>
   <NumberOfReports>0</NumberOfReports> 
 </T2>
 <T2>
   <EmpId>2</EmpId>
   <EmpName>N2</EmpName>
   <MgrName>N2</MgrName>
   <NumberOfReports>1</NumberOfReports>
 </T2>
 <T2>
   <EmpId>3</EmpId>
   <EmpName>N3</EmpName>
   <MgrName>N3</MgrName>
   <NumberOfReports>1</NumberOfReports>
 </T2>
</NewDataSet>

»Ñ­ËÒ·Õè 3: àÁ×èÍÁÕàÃÕ¡ÇÔ¸Õ DataTable.Select â´Âãªé¤ÓÊÑè§ËÅÒ ¼ÅÅѾ¸ì·ÕèäÁè¶Ù¡µéͧÍÒ¨¶Ù¡Ê觡ÅѺ

string filter = "(NOT ColTwo = 1) AND (ColOne = 2)";
DataTable.Select(filter);

string filter = "NOT ColTwo = 1 AND ColOne = 2";
DataTable.Select(filter);

1. ¤Ø³ÊÒÁÒöãªéÃËÑʴѧµèÍ仹Õéã¹á;ÅÔपѹ:

   public static void Main()
   {
     DataTable table = new DataTable();
     table.Columns.Add("ColID", typeof(int));
     table.Columns.Add("ColOne", typeof(int));
     table.Columns.Add("ColTwo", typeof(int));
     table.Rows.Add(new object[] { 1, 1, 1 });
     table.Rows.Add(new object[] { 2, 1, 2 });
     table.Rows.Add(new object[] { 3, 2, 1 });
     table.Rows.Add(new object[] { 4, 2, 2 });
   
     string[] queries = new string[] {
         "(NOT ColTwo = 1) AND (ColOne = 2)",
         "(ColOne = 2) AND (NOT ColTwo = 1)",
   
         "NOT ColTwo = 1 AND ColOne = 2",
         "ColOne = 2 AND NOT ColTwo = 1",
   
         "NOT ColTwo = 1 AND (ColOne = 2)",
         "(ColOne = 2) AND NOT ColTwo = 1",
   
         "(NOT ColTwo = 1) AND ColOne = 2",
         "ColOne = 2 AND (NOT ColTwo = 1)",
     };
   
     Console.WriteLine("Select");
     foreach(string query in queries) {
         DataRow[] rows = table.Select(query);
         Console.WriteLine("query=\"{0}\" count={1}", query, rows.Length);
         foreach(DataRow row in rows) {
             Console.WriteLine("\t{0}, {1}, {2}", row[0], row[1], row[2]);
         }
     }
   }
   

2. ¤Ø³àÃÕ¡ãªéá;ÅÔपѹ

query="(NOT ColTwo = 1) AND (ColOne = 2)" count=2
        3, 2, 1
        4, 2, 2
query="(ColOne = 2) AND (NOT ColTwo = 1)" count=1
        4, 2, 2
query="NOT ColTwo = 1 AND ColOne = 2" count=1
        4, 2, 2
query="ColOne = 2 AND NOT ColTwo = 1" count=1
        4, 2, 2
query="NOT ColTwo = 1 AND (ColOne = 2)" count=2
        3, 2, 1
        4, 2, 2
query="(ColOne = 2) AND NOT ColTwo = 1" count=1
        4, 2, 2
query="(NOT ColTwo = 1) AND ColOne = 2" count=1
        4, 2, 2
query="ColOne = 2 AND (NOT ColTwo = 1)" count=1
        4, 2, 2

»Ñ­ËÒ·Õè 4: ´Ñª¹ÕÀÒÂ㹢ͧ DataTable ÍÒ¨àÊÕÂËÒ áÅФسä´éÃѺ¢éͤÇÒÁáÊ´§¢éͤÇÒÁ¢éͼԴ¾ÅÒ´ '13'

• Çѵ¶ØªØ´¢éÍÁÙÅ»ÃСͺ´éǵÒÃÒ§ÍÂèÒ§ ¹éÍÂ˹Ö觵ÒÃÒ§·ÕèÁÕ¤ÇÒÁÊÑÁ¾Ñ¹¸ìẺ˹Ö觵èÍ-¡ÅØèÁ
• AcceptChangesàÁ¸Í´¢Í§Çѵ¶ØªØ´¢éÍÁÙŹÑé¹
• µÑ駤èÒAcceptRejectRule¢Í§Çѵ¶ØªØ´¢éÍÁÙÅàÁ×è͵éͧ¡ÒÃàÃÕ§«é͹ àÁ×èÍÁÕµÑ駤èÒ¹Õéà»ç¹¡ÒÃàÃÕ§«é͹ µÒÃÒ§ÅÙ¡¨Ðà»ÅÕè¹á»Å§à¾×èÍãËéä´éâ´ÂÍѵâ¹ÁѵÔÍÂèÒ§ã´ÍÂèҧ˹Ö觢éÍÁÙÅÂÍÁÃѺ ËÃ×ÍäÁèÂÍÁÃѺ¢éÍÁÙÅ

1. ¤Ø³ÊÒÁÒöãªéÃËÑʴѧµèÍ仹Õéã¹á;ÅÔपѹ:

   public void Main()
   {
   			DataTable Table = new DataTable("Employee");
   			Table.Columns.Add("Id", typeof(int));
   			Table.Columns.Add("ManagerId", typeof(int));
   			Table.Columns.Add("Name", typeof(string));
   
   			Table.Columns["Name"].AllowDBNull = false;
   			Table.PrimaryKey = new DataColumn[] {Table.Columns["Id"]};
   
   			DataSet Employees = new DataSet();
   			Employees.Tables.Add(Table);
   
   			DataRelation rel = Employees.Relations.Add(Table.Columns["ID"], Table.Columns["ManagerId"]);
   			rel.ChildKeyConstraint.AcceptRejectRule = AcceptRejectRule.Cascade;
   
   			DataRow ManagerA = Table.NewRow();
   			ManagerA["ID"] = 2019;
   			ManagerA["Name"] = "Manager A";
   			Table.Rows.Add(ManagerA);
   
   			DataRow ManagerB = Table.NewRow();
   			ManagerB["ID"] = 392;
   			ManagerB["Name"] = "Manager B";
   			Table.Rows.Add(ManagerB);
   
   			DataRow EmployeeB = Table.NewRow();
   			EmployeeB["ID"] = 716;
   			EmployeeB["Name"] = "Employee of B";
   			EmployeeB.SetParentRow(ManagerB);
   			Table.Rows.Add(EmployeeB);
   
   			EmployeeB = Table.NewRow();
   			EmployeeB["ID"] = 637;
   			EmployeeB["Name"] = "2nd employee of B";
   			EmployeeB.SetParentRow(ManagerB);
   			Table.Rows.Add(EmployeeB);
   
   			Employees.AcceptChanges();
   			Table.Rows.Find(392).Delete();
   			Employees.AcceptChanges();
   }

2. ¤Ø³àÃÕ¡ãªéá;ÅÔपѹ

»Ñ­ËÒ·Õè 5: àÁ×èÍ¡ÒôÓà¹Ô¹¡ÒüÊÒ¹à¡Ô´¢Öé¹ µÑǨѴ¡ÒÃÃÐàºÕ¹ÍÒ¨àÊÕ¶éÒá¶Çà»éÒËÁÒÂÍÂÙèã¹Ê¶Ò¹Ðá¡éä¢

1. ¤Ø³ÊÒÁÒöãªéÃËÑʴѧµèÍ仹Õéã¹á;ÅÔपѹ:

   using System;
   using System.Data;
   using System.Collections.Generic;
   using System.Text;
   
   namespace ConsoleApplication1
   {
       class Program
       {
           static void Main(string[] args)
           {
               DataSet set = new DataSet();
               DataTable table = set.Tables.Add("table");
               table.Columns.Add("C1", typeof(int));
               table.Columns.Add("C2", typeof(char));
               table.PrimaryKey = new DataColumn[] { table.Columns[0] };
               for (int i = 0; i < 26; ++i)
               {
                   table.Rows.Add(new object[] { i, (char)((ushort)'a' + i) });
               }
               table.AcceptChanges();
   
               DataSet clone = set.Copy();
               clone.Tables[0].Rows[0][1] = 'Z';
               //clone.AcceptChanges();
   
               table.Rows[0][1] = '1';
               table.Rows[0].BeginEdit();
               table.Rows[0][1] = '2';
   
   
               try
               {
                   set.Merge(clone);
               }
               finally
               {
                  foreach (DataRow row in table.Rows) {
   																	Console.WriteLine("{0}={1}", row[0], row[1]);
   															}
               }
   
           }
       }
   }

2. ¤Ø³àÃÕ¡ãªéá;ÅÔपѹ

»Ñ­ËÒ·Õè 6: ´Ñª¹ÕÀÒÂ㹢ͧ DataTable Çѵ¶ØÍÒ¨àÊÕÂËÒ áÅФسä´éÃѺ¢éͤÇÒÁáÊ´§¢éͤÇÒÁ¢éͼԴ¾ÅÒ´ '5'

1. ¤èÒDataColumn.Expression¶Ù¡à»ÅÕ蹨ҡ¹Ô¾¨¹ì¨ÐäÁèÁÕ¹Ô¾¨¹ì ã¹Ê¶Ò¹¡ÒóìÊÁÁµÔ¹Õé ¢éÍÁÙÅ·Ñé§ËÁ´ã¹DataColumnÇѵ¶Ø¶Ù¡µÑ駤èÒà»ç¹ DBNull
2. àÁ×èÍÁÕàÃÕ¡ÇÔ¸ÕDataTable.Clear¢éÍÁÙÅ·Ñé§ËÁ´ã¹DataTableÇѵ¶Ø¨Ð¶Ù¡àÍÒÍÍ¡ áÅдѪ¹Õ¨Ð¶Ù¡»ÃѺ»Ãا ÍÂèÒ§äáçµÒÁ µÒÃÒ§Í×è¹ æ ·ÕèÍéÒ§ÍÔ§Çѵ¶ØDataTable¨ÐäÁè»ÃѺ»Ãا

1. ¤Ø³ÊÒÁÒöãªéÃËÑʴѧµèÍ仹Õéã¹á;ÅÔपѹ:

   using System;
   using System.Data;
   using System.Collections.Generic;
   using System.Text;
   
   namespace ConsoleApplication1
   {
       class Program
       {
           static void Main(string[] args)
           {
               DataSet set = new DataSet("s");
               DataTable table1 = set.Tables.Add("a");
               table1.Columns.Add("C1", typeof(int));
               table1.Columns.Add("C2", typeof(int));
               table1.DefaultView.Sort = "C2";
   
               DataTable table2 = set.Tables.Add("b");
               table2.Columns.Add("C1", typeof(int));
               table2.Columns.Add("C2", typeof(int));
               table2.DefaultView.Sort = "C2";
   
               set.Relations.Add(new DataRelation("t1t2", table1.Columns[0], table2.Columns[0], false));
               table1.Columns[1].Expression = "Sum(Child(t1t2).C2)";
   
               AddData(table1, 1);
               AddData(table2, 2);
   
               table1.Columns[1].Expression = null;
   
               AddData(table2, 2);
               AddData(table1, 2);
   
           }
           private static void AddData(DataTable table, int y)
           {
               object[] x = new object[y];
               Random rand = new Random(20070125);
               for (int i = 0; i < 1000; ++i)
               {
                   switch (rand.Next(3))
                   {
                       case 0:
                       case 1:
                           for (int k = 0; k < x.Length; ++k)
                           {
                               x[k] = rand.Next(500);
                           }
                           table.Rows.Add(x);
                           break;
                       case 2:
                           if (0 < table.Rows.Count)
                           {
                               table.Rows.RemoveAt(rand.Next(table.Rows.Count));
                           }
                           break;
                   }
               }
           }
   
       }
   }
   
   

2. ¤Ø³àÃÕ¡ãªéá;ÅÔपѹ

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