DataTable.Clone メソッド
定義
重要
一部の情報は、リリース前に大きく変更される可能性があるプレリリースされた製品に関するものです。 Microsoft は、ここに記載されている情報について、明示または黙示を問わず、一切保証しません。
public:
virtual System::Data::DataTable ^ Clone();public virtual System.Data.DataTable Clone ();abstract member Clone : unit -> System.Data.DataTable
override this.Clone : unit -> System.Data.DataTablePublic Overridable Function Clone () As DataTable戻り値
現在の DataTable と同じスキーマを持つ新しい DataTable。
例
次の例では、DataTable.Clone を実行した後に、変換先テーブルの構造と制約を更新する方法を示します。 ClonedDataTable クラスは、変換先テーブルを返し、更新中のすべてのイベントを含みます。 複製後、ソース テーブルの構造の変更は、コピー先テーブルには反映されません。 具体的には、このサンプルでは次の操作を行います。
ソース テーブルの列の変更を更新します。
ソース テーブルの UniqueConstraint の変更を更新します。
ソース テーブルの ForeignKeyConstraint の変更を更新します。
using System;
using System.Linq;
using System.Data;
using System.ComponentModel;
class Program {
static void Main(string[] args) {
DataTable courses = NewCourseDataTable();
Console.WriteLine("This is the source table:");
WriteDataTable(courses);
ClonedDataTable clonedResult = new ClonedDataTable(courses);
DataTable clonedCourses = clonedResult.DestinationTable;
Console.WriteLine("This is the destination table:");
WriteDataTable(clonedCourses);
// Add the events of updating column collection into the source table.
clonedResult.UpdateAddedColumn();
clonedResult.UpdateDeletedColumn();
// Add a DataColumn in source table.
DataColumn columnCredits = new DataColumn("Credits", typeof(Int32));
courses.Columns.Add(columnCredits);
Console.WriteLine("After add a column in source table, it's the result in the destination:");
WriteDataTable(clonedCourses);
// Add the event of updating UniqueConstraint into the source table.
clonedResult.UpdateUniqueConstraint();
// Add the unique constraint in source table.
UniqueConstraint uniqueConstraint = new UniqueConstraint(courses.Columns["CourseId"]);
courses.Constraints.Add(uniqueConstraint);
Console.WriteLine(@"If we add the unique constraint in source table and then insert the duplicate
rows into the destination table, we will get the following error:");
InsertDuplicateData(clonedCourses);
Console.WriteLine();
// Add the event of updating ForeignKeyConstraint into the source table.
clonedResult.UpdateForeignKeyConstraint();
// Add the ForeignKeyConstraint into the source table.
DataTable departments = NewDepartmentDataTable();
DataSet dataset = new DataSet();
dataset.Tables.Add(courses);
dataset.Tables.Add(clonedCourses);
dataset.Tables.Add(departments);
ForeignKeyConstraint foreignKey = new ForeignKeyConstraint(departments.Columns["DepartmentId"], courses.Columns["DepartmentId"]);
courses.Constraints.Add(foreignKey);
Console.WriteLine(@"If we add the foreign key constraint in source table and then insert a row
without the parent into the destination table, we will get the following error:");
InsertNoParentRow(clonedCourses);
Console.WriteLine();
Console.WriteLine("Please press any key to exit...");
Console.ReadKey();
}
static private DataTable NewCourseDataTable() {
DataTable newTable = new DataTable();
DataColumn[] columns ={
new DataColumn("CourseId", typeof(String)),
new DataColumn("CourseName",typeof(String)),
new DataColumn("DepartmentId", typeof(Int32))
};
newTable.Columns.AddRange(columns);
newTable.Rows.Add("C1045", "Calculus", 7);
newTable.Rows.Add("C1061", "Physics", 1);
newTable.Rows.Add("C2021", "Composition", 2);
newTable.Rows.Add("C2042", "Literature", 2);
return newTable;
}
static private DataTable NewDeparmentDataTable() {
DataTable newTable = new DataTable();
DataColumn[] columns ={
new DataColumn("DepartmentId", typeof(Int32)),
new DataColumn("Name",typeof(String)),
};
newTable.Columns.AddRange(columns);
newTable.Rows.Add(1, "Engineering");
newTable.Rows.Add(2, "English");
newTable.Rows.Add(4, "Economics");
newTable.Rows.Add(7, "Mathematics");
return newTable;
}
static private void WriteDataTable(DataTable table) {
if (table == null)
return;
foreach (DataColumn column in table.Columns) {
Console.Write("{0,-15}", column.ColumnName);
}
Console.WriteLine();
foreach (DataRow row in table.Rows) {
for (int i = 0; i < table.Columns.Count; i++)
Console.Write("{0,-15}", row[i].ToString());
Console.WriteLine();
}
Console.WriteLine();
}
static private void InsertDuplicateData(DataTable table) {
try {
table.Rows.Add("C1045", "Calculus", 7);
table.Rows.Add("C1045", "Calculus", 7);
} catch (Exception e) {
Console.WriteLine("\"" + e.Message + "\"");
}
}
private static void InsertNoParentRow(DataTable table) {
try {
table.Rows.Add("C1061", "Physics", 11);
} catch (Exception e) {
Console.WriteLine("\"" + e.Message + "\"");
}
}
}
public class ClonedDataTable {
private DataTable sourceTable;
private DataTable destinationTable;
public ClonedDataTable(DataTable source) {
sourceTable = source;
// set the cloned result
destinationTable = sourceTable.Clone();
}
public void UpdateAddedColumn() {
sourceTable.Columns.CollectionChanged += new CollectionChangeEventHandler(ColumnAdded);
}
public void UpdateDeletedColumn() {
sourceTable.Columns.CollectionChanged += new CollectionChangeEventHandler(ColumnDeleted);
}
public void UpdateUniqueConstraint() {
sourceTable.Constraints.CollectionChanged += new CollectionChangeEventHandler(UniqueConstraint_Changed);
}
public void UpdateForeignKeyConstraint() {
sourceTable.Constraints.CollectionChanged += new CollectionChangeEventHandler(ForeignKeyConstraint_Changed);
}
// After the source table adds a column, the method will add the same column in the destination table.
void ColumnAdded(object sender, System.ComponentModel.CollectionChangeEventArgs e) {
if (e.Action == CollectionChangeAction.Add) {
DataColumn column = e.Element as DataColumn;
if (column != null) {
DataColumn newColumn = new DataColumn(column.ColumnName, column.DataType, column.Expression, column.ColumnMapping);
if (!destinationTable.Columns.Contains(newColumn.ColumnName))
destinationTable.Columns.Add(newColumn);
}
}
}
// After the source table deletes a column, the method will delete the same column in the destination table.
void ColumnDeleted(object sender, CollectionChangeEventArgs e) {
if (e.Action == CollectionChangeAction.Remove) {
DataColumn column = e.Element as DataColumn;
if (column != null)
if (destinationTable.Columns.Contains(column.ColumnName))
destinationTable.Columns.Remove(column.ColumnName);
}
}
// After the source table changes the UniqueConstraint, this method changes the same UniqueConstraint in destination table.
void UniqueConstraint_Changed(object sender, CollectionChangeEventArgs e) {
UniqueConstraint constraint = e.Element as UniqueConstraint;
if (constraint == null)
return;
String constraintName = constraint.ConstraintName;
if (e.Action == CollectionChangeAction.Add) {
DataColumn[] columns = new DataColumn[constraint.Columns.Count()];
Boolean isPrimaryKey = constraint.IsPrimaryKey;
// Get the columns used in new constraint from the destination table.
for (Int32 i = 0; i < constraint.Columns.Count(); i++) {
String columnName = constraint.Columns[i].ColumnName;
if (destinationTable.Columns.Contains(columnName))
columns[i] = destinationTable.Columns[columnName];
else
return;
}
UniqueConstraint newConstraint = new UniqueConstraint(constraintName, columns, isPrimaryKey);
if (!destinationTable.Constraints.Contains(constraintName))
destinationTable.Constraints.Add(newConstraint);
} else if (e.Action == CollectionChangeAction.Remove)
if (destinationTable.Constraints.Contains(constraintName))
destinationTable.Constraints.Remove(constraintName);
}
// After the source table changes the ForeignKeyConstraint, this method changes
// the same ForeignKeyConstraint in the destination table.
void ForeignKeyConstraint_Changed(object sender, CollectionChangeEventArgs e) {
ForeignKeyConstraint constraint = e.Element as ForeignKeyConstraint;
if (constraint == null)
return;
// If the source and destination are not in the same DataSet, don't change the ForeignKeyConstraint.
if (sourceTable.DataSet != destinationTable.DataSet)
return;
String constraintName = constraint.ConstraintName;
if (e.Action == CollectionChangeAction.Add) {
DataColumn[] columns = new DataColumn[constraint.Columns.Count()];
DataColumn[] parentColumns = constraint.RelatedColumns;
// Get the columns used in new constraint from the destination table.
for (int i = 0; i < constraint.Columns.Count(); i++) {
String columnName = constraint.Columns[i].ColumnName;
if (destinationTable.Columns.Contains(columnName))
columns[i] = destinationTable.Columns[columnName];
else
return;
}
ForeignKeyConstraint newConstraint = new ForeignKeyConstraint(constraintName, parentColumns, columns);
newConstraint.AcceptRejectRule = constraint.AcceptRejectRule;
newConstraint.DeleteRule = constraint.DeleteRule;
newConstraint.UpdateRule = constraint.UpdateRule;
if (!destinationTable.Constraints.Contains(constraintName))
destinationTable.Constraints.Add(newConstraint);
} else if (e.Action == CollectionChangeAction.Remove)
if (destinationTable.Constraints.Contains(constraintName))
destinationTable.Constraints.Remove(constraintName);
}
// return the destination table.
public DataTable DestinationTable {
get { return destinationTable; }
}
}
このサンプルでは、DataTable 内のデータを変更し、データ ソースを更新する方法を示します。
まず、データベースを作成します。
USE [master]
GO
CREATE DATABASE [MySchool]
GO
USE [MySchool]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Course]([CourseID] [nvarchar](10) NOT NULL,
[Year] [smallint] NOT NULL,
[Title] [nvarchar](100) NOT NULL,
[Credits] [int] NOT NULL,
[DepartmentID] [int] NOT NULL,
CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED
(
[CourseID] ASC,
[Year] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Department]([DepartmentID] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](50) NOT NULL,
[Budget] [money] NOT NULL,
[StartDate] [datetime] NOT NULL,
[Administrator] [int] NULL,
CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED
(
[DepartmentID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
GO
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C1045', 2012, N'Calculus', 4, 7)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C1061', 2012, N'Physics', 4, 1)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C2021', 2012, N'Composition', 3, 2)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C2042', 2012, N'Literature', 4, 2)
SET IDENTITY_INSERT [dbo].[Department] ON
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (1, N'Engineering', 350000.0000, CAST(0x0000999C00000000 AS DateTime), 2)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (2, N'English', 120000.0000, CAST(0x0000999C00000000 AS DateTime), 6)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (4, N'Economics', 200000.0000, CAST(0x0000999C00000000 AS DateTime), 4)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (7, N'Mathematics', 250024.0000, CAST(0x0000999C00000000 AS DateTime), 3)
SET IDENTITY_INSERT [dbo].[Department] OFF
ALTER TABLE [dbo].[Course] WITH CHECK ADD CONSTRAINT [FK_Course_Department] FOREIGN KEY([DepartmentID])
REFERENCES [dbo].[Department] ([DepartmentID])
GO
ALTER TABLE [dbo].[Course] CHECK CONSTRAINT [FK_Course_Department]
GO
using System;
using System.Data;
using System.Data.SqlClient;
class Program {
static void Main(string[] args) {
string MySchoolConnectionString = "Data Source=(local);Initial Catalog=MySchool;Integrated Security=True";
// Get Data
String selectString =
@"Select [CourseID],[Year],[Title],[Credits],[DepartmentID] From [dbo].[Course];
Select [DepartmentID],[Name],[Budget],[StartDate],[Administrator] From [dbo].[Department] ";
DataSet dataSet = new DataSet();
DataTable course = dataSet.Tables.Add("Course");
DataTable department = dataSet.Tables.Add("Department");
Console.WriteLine("Get data from database:");
GetDataTables(MySchoolConnectionString, selectString, dataSet, course, department);
Console.WriteLine();
// Use DataTable Edits to edit the data
String updateString =
@"Update [dbo].[Course] Set [Credits]=@Credits Where [CourseID]=@CourseID;";
course.ColumnChanged += OnColumnChanged;
// Set the Credits of first row is negative value, and set the Credits of second row is plus.
ChangeCredits(course, course.Rows[0], -1);
ChangeCredits(course, course.Rows[1], 11);
UpdateDataTables(MySchoolConnectionString, updateString, dataSet, "Course",
new SqlParameter("@CourseID", SqlDbType.NVarChar, 10, "CourseID"),
new SqlParameter("@Credits", SqlDbType.Int, 4, "Credits"));
Console.WriteLine("Only the Credits of second row is changed.");
ShowDataTable(course);
Console.WriteLine();
// Delete and Remove from DataTable
// Create the foreign key constraint, and set the DeleteRule with Cascade.
ForeignKeyConstraint courseDepartFK = new ForeignKeyConstraint("CourseDepartFK", department.Columns["DepartmentID"], course.Columns["DepartmentID"]);
courseDepartFK.DeleteRule = Rule.Cascade;
courseDepartFK.UpdateRule = Rule.Cascade;
courseDepartFK.AcceptRejectRule = AcceptRejectRule.None;
course.Constraints.Add(courseDepartFK);
String deleteString = @"Delete From [dbo].[Course] Where [CourseID]=@CourseID;";
department.Rows[0].Delete();
Console.WriteLine("If One row in Department table is deleted, the related rows in Course table will also be deleted.");
Console.WriteLine("Department DataTable:");
ShowDataTable(department);
Console.WriteLine();
Console.WriteLine("Course DataTable:");
ShowDataTable(course);
Console.WriteLine();
// Update the delete operation
DeleteDataTables(MySchoolConnectionString, deleteString, dataSet, "Course",
new SqlParameter("@CourseID", SqlDbType.NVarChar, 10, "CourseID"));
Console.WriteLine("After delete operation:");
Console.WriteLine("Course DataTable:");
ShowDataTable(course);
Console.WriteLine();
course.Rows.RemoveAt(0);
Console.WriteLine("Now we remove one row from Course:");
ShowDataTable(course);
DeleteDataTables(MySchoolConnectionString, deleteString, dataSet, "Course",
new SqlParameter("@CourseID", SqlDbType.NVarChar, 10, "CourseID"));
}
// Use SqlDataAdapter to get data.
private static void GetDataTables(String connectionString, String selectString,
DataSet dataSet, params DataTable[] tables) {
using (SqlDataAdapter adapter = new SqlDataAdapter()) {
adapter.SelectCommand = new SqlCommand(selectString);
adapter.SelectCommand.Connection = new SqlConnection(connectionString);
adapter.Fill(0, 0, tables);
foreach (DataTable table in dataSet.Tables) {
Console.WriteLine("Data in {0}:", table.TableName);
ShowDataTable(table);
Console.WriteLine();
}
}
}
// Use SqlDataAdapter to update the updata operation.
private static void UpdateDataTables(String connectionString, String updateString,
DataSet dataSet, String tableName, params SqlParameter[] parameters) {
using (SqlDataAdapter adapter = new SqlDataAdapter()) {
adapter.UpdateCommand = new SqlCommand(updateString);
adapter.UpdateCommand.Parameters.AddRange(parameters);
adapter.UpdateCommand.Connection = new SqlConnection(connectionString);
adapter.Update(dataSet, tableName);
}
}
// Use SqlDataAdapter to update delete operation.
private static void DeleteDataTables(String connectionString, String deleteString,
DataSet dataSet, String tableName, params SqlParameter[] parameters) {
using (SqlDataAdapter adapter = new SqlDataAdapter()) {
adapter.DeleteCommand = new SqlCommand(deleteString);
adapter.DeleteCommand.Parameters.AddRange(parameters);
adapter.DeleteCommand.Connection = new SqlConnection(connectionString);
adapter.Update(dataSet, tableName);
}
}
// Use DataTable Edits to modify the data.
private static void ChangeCredits(DataTable table, DataRow row, Int32 credits) {
row.BeginEdit();
Console.WriteLine("We change row {0}", table.Rows.IndexOf(row));
row["Credits"] = credits;
row.EndEdit();
}
// The method will be invoked when the value in DataTable is changed.
private static void OnColumnChanged(Object sender, DataColumnChangeEventArgs args) {
Int32 credits = 0;
// If Credits is changed and the value is negative, we'll cancel the edit.
if ((args.Column.ColumnName == "Credits") &&
(!Int32.TryParse(args.ProposedValue.ToString(), out credits) || credits < 0)) {
Console.WriteLine("The value of Credits is invalid. Edit canceled.");
args.Row.CancelEdit();
}
}
// Display the column and value of DataTable.
private static void ShowDataTable(DataTable table) {
foreach (DataColumn col in table.Columns) {
Console.Write("{0,-14}", col.ColumnName);
}
Console.WriteLine("{0,-14}", "RowState");
foreach (DataRow row in table.Rows) {
if (row.RowState == DataRowState.Deleted) {
foreach (DataColumn col in table.Columns) {
if (col.DataType.Equals(typeof(DateTime)))
Console.Write("{0,-14:d}", row[col, DataRowVersion.Original]);
else if (col.DataType.Equals(typeof(Decimal)))
Console.Write("{0,-14:C}", row[col, DataRowVersion.Original]);
else
Console.Write("{0,-14}", row[col, DataRowVersion.Original]);
}
}
else {
foreach (DataColumn col in table.Columns) {
if (col.DataType.Equals(typeof(DateTime)))
Console.Write("{0,-14:d}", row[col]);
else if (col.DataType.Equals(typeof(Decimal)))
Console.Write("{0,-14:C}", row[col]);
else
Console.Write("{0,-14}", row[col]);
}
}
Console.WriteLine("{0,-14}", row.RowState);
}
}
}
注釈
これらのクラスが派生している場合、複製も同じ派生クラスになります。
Clone では、元DataTableの と同じ構造を持つ新しい DataTable が作成されますが、データはコピーされません (新しい DataTable には がDataRows含まれません)。 構造体とデータの両方を新しい DataTableにコピーするには、 を使用します Copy。
適用対象
こちらもご覧ください
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