Export (0) Print
Expand All

DataTableReader Constructor (DataTable())

Initializes a new instance of the DataTableReader class using the supplied array of DataTable objects.

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

'Declaration
Public Sub New ( _
	dataTables As DataTable() _
)

Parameters

dataTables
Type: System.Data.DataTable()

The array of DataTable objects that supplies the results for the new DataTableReader object.

If you must create a DataTableReader based on all or a subset of the tables within a specific Dataset, call the DataSet's GetDataReader method. If you want to create a new DataTableReader instance based on a group of DataTable instances that are not otherwise related, use this constructor. You can also take advantage of this constructor to rearrange the ordering of the DataTables within the DataTableReader, if their ordering within their source DataSet does not meet your needs.

In the following example, the TestConstructor method creates two DataTable instances. In order to demonstrate this constructor for the DataTableReader class, the sample creates a new DataTableReader based on an array that contains the two DataTables, and performs a simple operation, printing the contents from the first few columns to the console window. In order to test this application, create a new Console application, and paste the sample code into the newly created file.

Private Sub TestConstructor()
   ' Create two data adapters, one for each of the two 
   ' DataTables to be filled. 
   Dim customerDataTable As DataTable = GetCustomers()
   Dim productDataTable As DataTable = GetProducts()

   ' Create the new DataTableReader. 
   Using reader As New DataTableReader( _
      New DataTable() {customerDataTable, productDataTable})

      ' Print the contents of each of the result sets. 
      Do
         PrintColumns(reader)
      Loop While reader.NextResult()
   End Using

   Console.WriteLine("Press Enter to finish.")
   Console.ReadLine()

End Sub 

Private Function GetCustomers() As DataTable
   ' Create sample Customers table, in order 
   ' to demonstrate the behavior of the DataTableReader. 
   Dim table As New DataTable

   ' 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() {1, "Mary"})
   table.Rows.Add(New Object() {2, "Andy"})
   table.Rows.Add(New Object() {3, "Peter"})
   table.Rows.Add(New Object() {4, "Russ"})
   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

   ' 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() {1, "Wireless Network Card"})
   table.Rows.Add(New Object() {2, "Hard Drive"})
   table.Rows.Add(New Object() {3, "Monitor"})
   table.Rows.Add(New Object() {4, "CPU"})
   Return table
End Function 

Private Sub PrintColumns( _
   ByVal reader As DataTableReader)

   ' Loop through all the rows in the DataTableReader. 
   Do While reader.Read()
      For i As Integer = 0 To reader.FieldCount - 1
         Console.Write(reader(i).ToString() & " ")
      Next
      Console.WriteLine()
   Loop 
End Sub

The Console window displays the following results:

1 Mary
2 Andy
3 Peter
4 Russ
1 Wireless Network Card
2 Hard Drive
3 Monitor
4 CPU

.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.

Show:
© 2014 Microsoft