本文整理汇总了C#中System.Data.DataTable.Load方法的典型用法代码示例。如果您正苦于以下问题：C# DataTable.Load方法的具体用法？C# DataTable.Load怎么用？C# DataTable.Load使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类System.Data.DataTable的用法示例。
在下文中一共展示了DataTable.Load方法的4个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C#代码示例。
示例1: Main
static void Main()
{
// This example examines a number of scenarios involving the
// DataTable.Load method.
Console.WriteLine("Load a DataTable and infer its schema:");
// The table has no schema. The Load method will infer the
// schema from the IDataReader:
DataTable table = new DataTable();
// Retrieve a data reader, based on the Customers data. In
// an application, this data might be coming from a middle-tier
// business object:
DataTableReader reader = new DataTableReader(GetCustomers());
table.Load(reader);
PrintColumns(table);
Console.WriteLine(" ============================= ");
Console.WriteLine("Load a DataTable from an incompatible IDataReader:");
// Create a table with a single integer column. Attempt
// to load data from a reader with a schema that is
// incompatible. Note the exception, determined
// by the particular incompatibility:
table = GetIntegerTable();
reader = new DataTableReader(GetStringTable());
try
{
table.Load(reader);
}
catch (Exception ex)
{
Console.WriteLine(ex.GetType().Name + ":" + ex.Message);
}
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable with an IDataReader that has extra columns:");
// Note that loading a reader with extra columns adds
// the columns to the existing table, if possible:
table = GetIntegerTable();
reader = new DataTableReader(GetCustomers());
table.Load(reader);
PrintColumns(table);
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable with an IDataReader that has missing columns:");
// Note that loading a reader with missing columns causes
// the columns to be filled with null data, if possible:
table = GetCustomers();
reader = new DataTableReader(GetIntegerTable());
table.Load(reader);
PrintColumns(table);
// Demonstrate the various possibilites when loading data into
// a DataTable that already contains data.
Console.WriteLine(" ============================= ");
Console.WriteLine("Demonstrate data considerations:");
Console.WriteLine("Current value, Original value, (RowState)");
Console.WriteLine(" ============================= ");
Console.WriteLine("Original table:");
table = SetupModifiedRows();
DisplayRowState(table);
Console.WriteLine(" ============================= ");
Console.WriteLine("Data in IDataReader to be loaded:");
DisplayRowState(GetChangedCustomers());
PerformDemo(LoadOption.OverwriteChanges);
PerformDemo(LoadOption.PreserveChanges);
PerformDemo(LoadOption.Upsert);
Console.WriteLine("Press any key to continue.");
Console.ReadKey();
}
private static void DisplayRowState(DataTable table)
{
for (int i = 0; i <= table.Rows.Count - 1; i++)
{
object current = "--";
object original = "--";
DataRowState rowState = table.Rows[i].RowState;
// Attempt to retrieve the current value, which doesn't exist
// for deleted rows:
if (rowState != DataRowState.Deleted)
{
current = table.Rows[i]["Name", DataRowVersion.Current];
}
// Attempt to retrieve the original value, which doesn't exist
// for added rows:
if (rowState != DataRowState.Added)
{
original = table.Rows[i]["Name", DataRowVersion.Original];
}
Console.WriteLine("{0}: {1}, {2} ({3})", i, current,
original, rowState);
}
}
private static DataTable GetChangedCustomers()
{
// Create sample Customers table.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
table.Columns.Add("Name", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 0, "XXX" });
table.Rows.Add(new object[] { 1, "XXX" });
table.Rows.Add(new object[] { 2, "XXX" });
table.Rows.Add(new object[] { 3, "XXX" });
table.Rows.Add(new object[] { 4, "XXX" });
table.AcceptChanges();
return table;
}
private static DataTable GetCustomers()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
table.Columns.Add("Name", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 0, "Mary" });
table.Rows.Add(new object[] { 1, "Andy" });
table.Rows.Add(new object[] { 2, "Peter" });
table.AcceptChanges();
return table;
}
private static DataTable GetIntegerTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 4 });
table.Rows.Add(new object[] { 5 });
table.AcceptChanges();
return table;
}
private static DataTable GetStringTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { "Mary" });
table.Rows.Add(new object[] { "Andy" });
table.Rows.Add(new object[] { "Peter" });
table.AcceptChanges();
return table;
}
private static void PerformDemo(LoadOption optionForLoad)
{
// Load data into a DataTable, retrieve a DataTableReader containing
// different data, and call the Load method. Depending on the
// LoadOption value passed as a parameter, this procedure displays
// different results in the DataTable.
Console.WriteLine(" ============================= ");
Console.WriteLine("table.Load(reader, {0})", optionForLoad);
Console.WriteLine(" ============================= ");
DataTable table = SetupModifiedRows();
DataTableReader reader = new DataTableReader(GetChangedCustomers());
table.RowChanging +=new DataRowChangeEventHandler(HandleRowChanging);
table.Load(reader, optionForLoad);
Console.WriteLine();
DisplayRowState(table);
}
private static void PrintColumns(DataTable table)
{
// Loop through all the rows in the DataTableReader
foreach (DataRow row in table.Rows)
{
for (int i = 0; i < table.Columns.Count; i++)
{
Console.Write(row[i] + " ");
}
Console.WriteLine();
}
}
private static DataTable SetupModifiedRows()
{
// Fill a DataTable with customer info, and
// then modify, delete, and add rows.
DataTable table = GetCustomers();
// Row 0 is unmodified.
// Row 1 is modified.
// Row 2 is deleted.
// Row 3 is added.
table.Rows[1]["Name"] = "Sydney";
table.Rows[2].Delete();
DataRow row = table.NewRow();
row["ID"] = 3;
row["Name"] = "Melony";
table.Rows.Add(row);
// Note that the code doesn't call
// table.AcceptChanges()
return table;
}
static void HandleRowChanging(object sender, DataRowChangeEventArgs e)
{
Console.WriteLine(
"RowChanging event: ID = {0}, action = {1}", e.Row["ID"],
e.Action);
}示例2: Main
static void Main()
{
// This example examines a number of scenarios involving the
// DataTable.Load method.
Console.WriteLine("Load a DataTable and infer its schema:");
// The table has no schema. The Load method will infer the
// schema from the IDataReader:
DataTable table = new DataTable();
// Retrieve a data reader, based on the Customers data. In
// an application, this data might be coming from a middle-tier
// business object:
DataTableReader reader = new DataTableReader(GetCustomers());
table.Load(reader);
PrintColumns(table);
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable from an incompatible IDataReader:");
// Create a table with a single integer column. Attempt
// to load data from a reader with a schema that is
// incompatible. Note the exception, determined
// by the particular incompatibility:
table = GetIntegerTable();
reader = new DataTableReader(GetStringTable());
try
{
table.Load(reader);
}
catch (Exception ex)
{
Console.WriteLine(ex.GetType().Name + ":" + ex.Message);
}
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable with an IDataReader that has extra columns:");
// Note that loading a reader with extra columns adds
// the columns to the existing table, if possible:
table = GetIntegerTable();
reader = new DataTableReader(GetCustomers());
table.Load(reader);
PrintColumns(table);
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable with an IDataReader that has missing columns:");
// Note that loading a reader with missing columns causes
// the columns to be filled with null data, if possible:
table = GetCustomers();
reader = new DataTableReader(GetIntegerTable());
table.Load(reader);
PrintColumns(table);
// Demonstrate the various possibilites when loading data
// into a DataTable that already contains data.
Console.WriteLine(" ============================= ");
Console.WriteLine("Demonstrate data considerations:");
Console.WriteLine("Current value, Original value, (RowState)");
Console.WriteLine(" ============================= ");
Console.WriteLine("Original table:");
table = SetupModifiedRows();
DisplayRowState(table);
Console.WriteLine(" ============================= ");
Console.WriteLine("Data in IDataReader to be loaded:");
DisplayRowState(GetChangedCustomers());
// Load data into a DataTable, retrieve a DataTableReader
// containing different data, and call the Load method.
Console.WriteLine(" ============================= ");
Console.WriteLine("table.Load(reader)");
Console.WriteLine(" ============================= ");
table = SetupModifiedRows();
reader = new DataTableReader(GetChangedCustomers());
table.Load(reader);
DisplayRowState(table);
Console.WriteLine("Press any key to continue.");
Console.ReadKey();
}
private static void DisplayRowState(DataTable table)
{
for (int i = 0; i <= table.Rows.Count - 1; i++)
{
object current = "--";
object original = "--";
DataRowState rowState = table.Rows[i].RowState;
// Attempt to retrieve the current value, which doesn't exist
// for deleted rows:
if (rowState != DataRowState.Deleted)
{
current = table.Rows[i]["Name", DataRowVersion.Current];
}
// Attempt to retrieve the original value, which doesn't exist
// for added rows:
if (rowState != DataRowState.Added)
{
original = table.Rows[i]["Name", DataRowVersion.Original];
}
Console.WriteLine("{0}: {1}, {2} ({3})", i,
current, original, rowState);
}
}
private static DataTable GetChangedCustomers()
{
// Create sample Customers table.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID",
typeof(int));
table.Columns.Add("Name", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 1, "XXX" });
table.Rows.Add(new object[] { 2, "XXX" });
table.Rows.Add(new object[] { 3, "XXX" });
table.Rows.Add(new object[] { 4, "XXX" });
table.Rows.Add(new object[] { 5, "XXX" });
table.Rows.Add(new object[] { 6, "XXX" });
table.AcceptChanges();
return table;
}
private static DataTable GetCustomers()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID",
typeof(int));
table.Columns.Add("Name", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 1, "Mary" });
table.Rows.Add(new object[] { 2, "Andy" });
table.Rows.Add(new object[] { 3, "Peter" });
table.Rows.Add(new object[] { 4, "Russ" });
table.AcceptChanges();
return table;
}
private static DataTable GetIntegerTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID",
typeof(int));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 5 });
table.Rows.Add(new object[] { 6 });
table.Rows.Add(new object[] { 7 });
table.Rows.Add(new object[] { 8 });
table.AcceptChanges();
return table;
}
private static DataTable GetStringTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID",
typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { "Mary" });
table.Rows.Add(new object[] { "Andy" });
table.Rows.Add(new object[] { "Peter" });
table.Rows.Add(new object[] { "Russ" });
table.AcceptChanges();
return table;
}
private static void PrintColumns(DataTable table)
{
// Loop through all the rows in the DataTableReader
foreach (DataRow row in table.Rows)
{
for (int i = 0; i < table.Columns.Count; i++)
{
Console.Write(row[i] + " ");
}
Console.WriteLine();
}
}
private static DataTable SetupModifiedRows()
{
// Fill a DataTable with customer info, and
// then modify, delete, and add rows.
DataTable table = GetCustomers();
// Row 0 is unmodified.
// Row 1 is modified.
// Row 2 is deleted.
// Row 5 is added.
table.Rows[1]["Name"] = "Sydney";
table.Rows[2].Delete();
DataRow row = table.NewRow();
row["ID"] = 5;
row["Name"] = "Melony";
table.Rows.Add(row);
// Note that the code doesn't call
// table.AcceptChanges()
return table;
}示例3: Main
static void Main()
{
// This example examines a number of scenarios involving the
// DataTable.Load method.
Console.WriteLine("Load a DataTable and infer its schema:");
// The table has no schema. The Load method will infer the
// schema from the IDataReader:
DataTable table = new DataTable();
// Retrieve a data reader, based on the Customers data. In
// an application, this data might be coming from a middle-tier
// business object:
DataTableReader reader = new DataTableReader(GetCustomers());
table.Load(reader);
PrintColumns(table);
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable from an incompatible IDataReader:");
// Create a table with a single integer column. Attempt
// to load data from a reader with a schema that is
// incompatible. Note the exception, determined
// by the particular incompatibility:
table = GetIntegerTable();
reader = new DataTableReader(GetStringTable());
try
{
table.Load(reader);
}
catch (Exception ex)
{
Console.WriteLine(ex.GetType().Name + ":" + ex.Message);
}
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable with an IDataReader that has extra columns:");
// Note that loading a reader with extra columns adds
// the columns to the existing table, if possible:
table = GetIntegerTable();
reader = new DataTableReader(GetCustomers());
table.Load(reader);
PrintColumns(table);
Console.WriteLine(" ============================= ");
Console.WriteLine(
"Load a DataTable with an IDataReader that has missing columns:");
// Note that loading a reader with missing columns causes
// the columns to be filled with null data, if possible:
table = GetCustomers();
reader = new DataTableReader(GetIntegerTable());
table.Load(reader);
PrintColumns(table);
// Demonstrate the various possibilites when loading data into
// a DataTable that already contains data.
Console.WriteLine(" ============================= ");
Console.WriteLine("Demonstrate data considerations:");
Console.WriteLine("Current value, Original value, (RowState)");
Console.WriteLine(" ============================= ");
Console.WriteLine("Original table:");
table = SetupModifiedRows();
DisplayRowState(table);
Console.WriteLine(" ============================= ");
Console.WriteLine("Data in IDataReader to be loaded:");
DisplayRowState(GetChangedCustomers());
PerformDemo(LoadOption.OverwriteChanges);
PerformDemo(LoadOption.PreserveChanges);
PerformDemo(LoadOption.Upsert);
Console.WriteLine("Press any key to continue.");
Console.ReadKey();
}
private static void DisplayRowState(DataTable table)
{
for (int i = 0; i <= table.Rows.Count - 1; i++)
{
object current = "--";
object original = "--";
DataRowState rowState = table.Rows[i].RowState;
// Attempt to retrieve the current value, which doesn't exist
// for deleted rows:
if (rowState != DataRowState.Deleted)
{
current = table.Rows[i]["Name", DataRowVersion.Current];
}
// Attempt to retrieve the original value, which doesn't exist
// for added rows:
if (rowState != DataRowState.Added)
{
original = table.Rows[i]["Name", DataRowVersion.Original];
}
Console.WriteLine("{0}: {1}, {2} ({3})", i,
current, original, rowState);
}
}
private static DataTable GetChangedCustomers()
{
// Create sample Customers table.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
table.Columns.Add("Name", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 0, "XXX" });
table.Rows.Add(new object[] { 1, "XXX" });
table.Rows.Add(new object[] { 2, "XXX" });
table.Rows.Add(new object[] { 3, "XXX" });
table.Rows.Add(new object[] { 4, "XXX" });
table.AcceptChanges();
return table;
}
private static DataTable GetCustomers()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
table.Columns.Add("Name", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 0, "Mary" });
table.Rows.Add(new object[] { 1, "Andy" });
table.Rows.Add(new object[] { 2, "Peter" });
table.AcceptChanges();
return table;
}
private static DataTable GetIntegerTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 4 });
table.Rows.Add(new object[] { 5 });
table.AcceptChanges();
return table;
}
private static DataTable GetStringTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { "Mary" });
table.Rows.Add(new object[] { "Andy" });
table.Rows.Add(new object[] { "Peter" });
table.AcceptChanges();
return table;
}
private static void PerformDemo(LoadOption optionForLoad)
{
// Load data into a DataTable, retrieve a DataTableReader containing
// different data, and call the Load method. Depending on the
// LoadOption value passed as a parameter, this procedure displays
// different results in the DataTable.
Console.WriteLine(" ============================= ");
Console.WriteLine("table.Load(reader, {0})", optionForLoad);
Console.WriteLine(" ============================= ");
DataTable table = SetupModifiedRows();
DataTableReader reader = new DataTableReader(GetChangedCustomers());
table.RowChanging +=new DataRowChangeEventHandler(HandleRowChanging);
table.Load(reader, optionForLoad);
Console.WriteLine();
DisplayRowState(table);
}
private static void PrintColumns(DataTable table)
{
// Loop through all the rows in the DataTableReader
foreach (DataRow row in table.Rows)
{
for (int i = 0; i < table.Columns.Count; i++)
{
Console.Write(row[i] + " ");
}
Console.WriteLine();
}
}
private static DataTable SetupModifiedRows()
{
// Fill a DataTable with customer info, and
// then modify, delete, and add rows.
DataTable table = GetCustomers();
// Row 0 is unmodified.
// Row 1 is modified.
// Row 2 is deleted.
// Row 3 is added.
table.Rows[1]["Name"] = "Sydney";
table.Rows[2].Delete();
DataRow row = table.NewRow();
row["ID"] = 3;
row["Name"] = "Melony";
table.Rows.Add(row);
// Note that the code doesn't call
// table.AcceptChanges()
return table;
}
static void HandleRowChanging(object sender, DataRowChangeEventArgs e)
{
Console.WriteLine(
"RowChanging event: ID = {0}, action = {1}", e.Row["ID"], e.Action);
}示例4: Main
static void Main()
{
// Attempt to load data from a data reader in which
// the schema is incompatible with the current schema.
// If you use exception handling, you won't get the chance
// to examine each row, and each individual table,
// as the Load method progresses.
// By taking advantage of the FillErrorEventHandler delegate,
// you can interact with the Load process as an error occurs,
// attempting to fix the problem, or simply continuing or quitting
// the Load process:
DataTable table = GetIntegerTable();
DataTableReader reader = new DataTableReader(GetStringTable());
table.Load(reader, LoadOption.OverwriteChanges, FillErrorHandler);
Console.WriteLine("Press any key to continue.");
Console.ReadKey();
}
private static DataTable GetIntegerTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(int));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { 4 });
table.Rows.Add(new object[] { 5 });
table.AcceptChanges();
return table;
}
private static DataTable GetStringTable()
{
// Create sample Customers table, in order
// to demonstrate the behavior of the DataTableReader.
DataTable table = new DataTable();
// Create two columns, ID and Name.
DataColumn idColumn = table.Columns.Add("ID", typeof(string));
// Set the ID column as the primary key column.
table.PrimaryKey = new DataColumn[] { idColumn };
table.Rows.Add(new object[] { "Mary" });
table.Rows.Add(new object[] { "Andy" });
table.Rows.Add(new object[] { "Peter" });
table.AcceptChanges();
return table;
}
static void FillErrorHandler(object sender, FillErrorEventArgs e)
{
// You can use the e.Errors value to determine exactly what
// went wrong.
if (e.Errors.GetType() == typeof(System.FormatException))
{
Console.WriteLine("Error when attempting to update the value: {0}",
e.Values[0]);
}
// Setting e.Continue to True tells the Load
// method to continue trying. Setting it to False
// indicates that an error has occurred, and the
// Load method raises the exception that got
// you here.
e.Continue = true;
}