DataSet.Load Method (IDataReader, LoadOption, DataTable())

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.

Namespace:  System.Data
Assembly:  System.Data (in System.Data.dll)

'Declaration
Public Sub Load ( _
	reader As IDataReader, _
	loadOption As LoadOption, _
	ParamArray tables As DataTable() _
)

Parameters

reader
Type: System.Data.IDataReader

An IDataReader that provides one or more result sets.

loadOption
Type: System.Data.LoadOption

A value from the LoadOption enumeration that indicates how rows already in the DataTable instances within the DataSet will be combined with incoming rows that share the same primary key.

tables
Type: System.Data.DataTable()

An array of DataTable instances, from which the Load method retrieves name and namespace information. Each of these tables must be a member of the DataTableCollection contained by this DataSet.

The Load method provides a technique for filling a single DataTable with data, retrieved from an IDataReader instance. This method provides the same functionality, but allows you to load multiple result sets from an IDataReader into multiple tables within a DataSet.

NoteNote

The load operation will fail with an InvalidOperationException if any of the source data columns in the incoming reader are computed columns.

The loadOption parameter allows you to specify how you want the imported data to interact with existing data, and can be any of the values from the LoadOption enumeration. See the documentation for the DataTable Load method for more information on using this parameter.

The tables parameter allows you to specify an array of DataTable instances, indicating the order of the tables corresponding to each result set loaded from the reader. The Load method fills each supplied DataTable instance with data from a single result set from the source data reader. After each result set, the Load method moves on to the next result set within the reader, until there are no more result sets.

The name resolution scheme for this method is the same as that followed by the Fill method of the DbDataAdapter class.

The following example creates a new DataSet, adds two DataTable instances to the DataSet, and then fills the DataSet using the Load method, retrieving data from a DataTableReader that contains two result sets. Finally, the example displays the contents of the tables in the console window.

Sub Main()
    Dim dataSet As New DataSet

    Dim customerTable As New DataTable
    Dim productTable As New DataTable

    ' This information is cosmetic, only.
    customerTable.TableName = "Customers"
    productTable.TableName = "Products" 

    ' Add the tables to the DataSet:
    dataSet.Tables.Add(customerTable)
    dataSet.Tables.Add(productTable)

    ' Load the data into the existing DataSet.  
    Dim reader As DataTableReader = GetReader()
    dataSet.Load(reader, LoadOption.OverwriteChanges, _
        customerTable, productTable)

    ' Print out the contents of each table: 
    For Each table As DataTable In dataSet.Tables
        PrintColumns(table)
    Next

    Console.WriteLine("Press any key to continue.")
    Console.ReadKey()
End Sub 

Private Function GetCustomers() As DataTable
    ' Create sample Customers table. 
    Dim table As New DataTable
    table.TableName = "Customers" 

    ' Create two columns, ID and Name. 
    Dim idColumn As DataColumn = table.Columns.Add("ID", _
        GetType(Integer))
    table.Columns.Add("Name", GetType(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
End Function 

Private Function GetProducts() As DataTable
    ' Create sample Products table, in order 
    ' to demonstrate the behavior of the DataTableReader. 
    Dim table As New DataTable
    table.TableName = "Products" 

    ' Create two columns, ID and Name. 
    Dim idColumn As DataColumn = table.Columns.Add("ID", _
        GetType(Integer))
    table.Columns.Add("Name", GetType(String))

    ' Set the ID column as the primary key column.
    table.PrimaryKey = New DataColumn() {idColumn}

    table.Rows.Add(New Object() {0, "Wireless Network Card"})
    table.Rows.Add(New Object() {1, "Hard Drive"})
    table.Rows.Add(New Object() {2, "Monitor"})
    table.Rows.Add(New Object() {3, "CPU"})
    Return table
End Function 

Private Function GetReader() As DataTableReader
    ' Return a DataTableReader containing multiple 
    ' result sets, just for the sake of this demo. 
    Dim dataSet As New DataSet
    dataSet.Tables.Add(GetCustomers())
    dataSet.Tables.Add(GetProducts())
    Return dataSet.CreateDataReader()
End Function 

Private Sub PrintColumns( _
   ByVal table As DataTable)

    Console.WriteLine()
    Console.WriteLine(table.TableName)
    Console.WriteLine("=========================")
    ' Loop through all the rows in the table. 
    For Each row As DataRow In table.Rows
        For Each col As DataColumn In table.Columns
            Console.Write(row(col).ToString() & " ")
        Next
        Console.WriteLine()
    Next 
End Sub

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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