System.Data Namespace Component DataSet Class Definition In this article Examples Remarks Constructors Properties Methods Events Explicit Interface Implementations Applies to .NET Core .NET Framework .NET Standard Xamarin.Android Xamarin.iOS Xamarin.Mac Thread Safety See also Examples Source/Reference
System.Data Namespace Component
The System.Data namespace provides access to classes that represent the ADO.NET architecture. ADO.NET lets you build components that efficiently manage data from multiple data sources.
[System.Serializable]
public class DataSet : System.ComponentModel.MarshalByValueComponent, System.ComponentModel.IListSource, System.ComponentModel.ISupportInitializeNotification, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable
The following example consists of several methods that, combined, create and fill a DataSet from the Northwind database.
C#
using System;
using System.Data;
using System.Data.SqlClient;
namespace Microsoft.AdoNet.DataSetDemo
{
class NorthwindDataSet
{
static void Main()
{
string connectionString = GetConnectionString();
ConnectToData(connectionString);
}
private static void ConnectToData(string connectionString)
{
//Create a SqlConnection to the Northwind database.
using (SqlConnection connection =
new SqlConnection(connectionString))
{
//Create a SqlDataAdapter for the Suppliers table.
SqlDataAdapter adapter = new SqlDataAdapter();
// A table mapping names the DataTable.
adapter.TableMappings.Add("Table", "Suppliers");
// Open the connection.
connection.Open();
Console.WriteLine("The SqlConnection is open.");
// Create a SqlCommand to retrieve Suppliers data.
SqlCommand command = new SqlCommand(
"SELECT SupplierID, CompanyName FROM dbo.Suppliers;",
connection);
command.CommandType = CommandType.Text;
// Set the SqlDataAdapter's SelectCommand.
adapter.SelectCommand = command;
// Fill the DataSet.
DataSet dataSet = new DataSet("Suppliers");
adapter.Fill(dataSet);
// Create a second Adapter and Command to get
// the Products table, a child table of Suppliers.
SqlDataAdapter productsAdapter = new SqlDataAdapter();
productsAdapter.TableMappings.Add("Table", "Products");
SqlCommand productsCommand = new SqlCommand(
"SELECT ProductID, SupplierID FROM dbo.Products;",
connection);
productsAdapter.SelectCommand = productsCommand;
// Fill the DataSet.
productsAdapter.Fill(dataSet);
// Close the connection.
connection.Close();
Console.WriteLine("The SqlConnection is closed.");
// Create a DataRelation to link the two tables
// based on the SupplierID.
DataColumn parentColumn =
dataSet.Tables["Suppliers"].Columns["SupplierID"];
DataColumn childColumn =
dataSet.Tables["Products"].Columns["SupplierID"];
DataRelation relation =
new System.Data.DataRelation("SuppliersProducts",
parentColumn, childColumn);
dataSet.Relations.Add(relation);
Console.WriteLine(
"The {0} DataRelation has been created.",
relation.RelationName);
}
}
static private string GetConnectionString()
{
// To avoid storing the connection string in your code,
// you can retrieve it from a configuration file.
return "Data Source=(local);Initial Catalog=Northwind;"
+ "Integrated Security=SSPI";
}
}
}
Whereas DataTable objects contain the data, the DataRelationCollection allows you to navigate though the table hierarchy. The tables are contained in a DataTableCollection accessed through the Tables property. When accessing DataTable objects,
note that they are conditionally case sensitive. For example, if one DataTable is named "mydatatable" and another is named "Mydatatable", a string used to search for one of the tables is regarded as case sensitive. However, if "mydatatable" exists and "Mydatatable" does not, the search string is regarded as case insensitive. For more information about working with DataTable objects, see Creating a DataTable.
A DataSet can read and write data and schema as XML documents. The data and schema can then be transported across HTTP and used by any application, on any platform that is XML-enabled. You can save the schema as an XML schema with the WriteXmlSchema method, and both schema and data can be saved using the WriteXml method. To read an XML document that includes both schema and data, use the ReadXml
method.
In a typical multiple-tier implementation, the steps for creating and refreshing a DataSet, and in turn, updating the original data are to:
Classes inherited from DataSet are not finalized by the garbage collector, because the finalizer has been suppressed in DataSet. The derived class can call the ReRegisterForFinalize method in its constructor to allow the class to be finalized by the garbage collector.
Fills a DataSet with values from a data source using the supplied IDataReader, using an array of DataTable instances to supply the schema and namespace information.
Fills a DataSet with values from a data source using the supplied IDataReader, using an array of DataTable instances to supply the schema and namespace information.
Fills a DataSet with values from a data source using the supplied IDataReader, using an array of strings to supply the names for the tables within the DataSet.
Merges an array of DataRow objects into the current DataSet, preserving or discarding changes in the DataSet and handling an incompatible schema according to the given arguments.
Merges a specified DataSet and its schema into the current DataSet, preserving or discarding any changes in this DataSet according to the given argument.
Merges a specified DataSet and its schema with the current DataSet, preserving or discarding changes in the current DataSet and handling an incompatible schema according to the given arguments.
Merges a specified DataTable and its schema into the current DataSet, preserving or discarding changes in the DataSet and handling an incompatible schema according to the given arguments.
Clears all tables and removes all relations, foreign constraints, and tables from the DataSet. Subclasses should override Reset() to restore a DataSet to its original state.
Writes the current data, and optionally the schema, for the DataSet using the specified Stream and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Writes the current data, and optionally the schema, for the DataSet to the specified file using the specified XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Writes the current data, and optionally the schema, for the DataSet using the specified TextWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Writes the current data, and optionally the schema, for the DataSet using the specified XmlWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
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