VB.NET DataSet.Load方法代碼示例

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

Sub Main()
  Dim dataSet As New DataSet
  Dim table As DataTable

  Dim reader As DataTableReader = GetReader()

  ' The tables listed as parameters for the Load method 
  ' should be in the same order as the tables within the IDataReader.
  dataSet.Load(reader, LoadOption.Upsert, "Customers", "Products")
  For Each table In dataSet.Tables
    PrintColumns(table)
  Next

  ' Now try the example with the DataSet
  ' already filled with data:
  dataSet = New DataSet
  dataSet.Tables.Add(GetCustomers())
  dataSet.Tables.Add(GetProducts())

  ' Retrieve a data reader containing changed data:
  reader = GetReader()

  ' Load the data into the existing DataSet. Retrieve the order of the
  ' the data in the reader from the
  ' list of table names in the parameters. If you specify
  ' a new table name here, the Load method will create
  ' a corresponding new table.
  dataSet.Load(reader, LoadOption.Upsert, "NewCustomers", "Products")
  For Each table 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

Sub Main()
  Dim dataSet As New DataSet
  Dim table As New DataTable()

  ' 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.:
  dataSet = New DataSet()
  table = GetIntegerTable()
  dataSet.Tables.Add(table)
  Dim reader As New DataTableReader(GetStringTable())
  dataSet.Load(reader, LoadOption.OverwriteChanges, _
      AddressOf FillErrorHandler, table)

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

Private Sub FillErrorHandler(ByVal sender As Object, _
  ByVal e As FillErrorEventArgs)
  ' You can use the e.Errors value to determine exactly what
  ' went wrong.
  If e.Errors.GetType Is GetType(System.FormatException) Then
    Console.WriteLine("Error when attempting to update the value: {0}", _
      e.Values(0))
  End If

  ' 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
End Sub

Private Function GetIntegerTable() As DataTable
  ' Create sample table with a single Int32 column.
  Dim table As New DataTable

  Dim idColumn As DataColumn = table.Columns.Add("ID", _
      GetType(Integer))

  ' 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.TableName = "IntegerTable"
  table.AcceptChanges()
  Return table
End Function

Private Function GetStringTable() As DataTable
  ' Create sample table with a single String column.
  Dim table As New DataTable

  Dim idColumn As DataColumn = table.Columns.Add("ID", _
      GetType(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
End Function

Private Sub PrintColumns( _
   ByVal table As DataTable)

  ' Loop through all the rows in the DataTableReader.
  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