datatables.vb

东软内部材料（六）ado .net相关

        Me.dsUntyped.DataSetName = "dsUntyped"
        Me.dsUntyped.Locale = New System.Globalization.CultureInfo("en-US")
        Me.dsUntyped.Tables.AddRange(New System.Data.DataTable() {Me.dtMaster, Me.dtChild})
        '
        'dtMaster
        '
        Me.dtMaster.Columns.AddRange(New System.Data.DataColumn() {Me.MasterID, Me.MasterValue})
        Me.dtMaster.TableName = "dtMaster"
        '
        'MasterValue
        '
        Me.MasterValue.Caption = "MasterValue"
        Me.MasterValue.ColumnName = "MasterValue"
        '
        'btnDataSet
        '
        Me.btnDataSet.Location = New System.Drawing.Point(416, 56)
        Me.btnDataSet.Name = "btnDataSet"
        Me.btnDataSet.Size = New System.Drawing.Size(96, 24)
        Me.btnDataSet.TabIndex = 4
        Me.btnDataSet.Text = "Dataset Table "
        '
        'lbEmployees
        '
        Me.lbEmployees.Location = New System.Drawing.Point(8, 24)
        Me.lbEmployees.Name = "lbEmployees"
        Me.lbEmployees.Size = New System.Drawing.Size(184, 95)
        Me.lbEmployees.TabIndex = 1
        '
        'dgOrders
        '
        Me.dgOrders.DataMember = ""
        Me.dgOrders.HeaderForeColor = System.Drawing.SystemColors.ControlText
        Me.dgOrders.Location = New System.Drawing.Point(8, 152)
        Me.dgOrders.Name = "dgOrders"
        Me.dgOrders.Size = New System.Drawing.Size(392, 208)
        Me.dgOrders.TabIndex = 3
        '
        'lblEmployees
        '
        Me.lblEmployees.AutoSize = True
        Me.lblEmployees.Font = New System.Drawing.Font("Microsoft Sans Serif", 8.25!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.lblEmployees.Location = New System.Drawing.Point(8, 8)
        Me.lblEmployees.Name = "lblEmployees"
        Me.lblEmployees.Size = New System.Drawing.Size(66, 13)
        Me.lblEmployees.TabIndex = 0
        Me.lblEmployees.Text = "Employees:"
        '
        'lblClients
        '
        Me.lblClients.AutoSize = True
        Me.lblClients.Font = New System.Drawing.Font("Microsoft Sans Serif", 8.25!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.lblClients.Location = New System.Drawing.Point(200, 8)
        Me.lblClients.Name = "lblClients"
        Me.lblClients.Size = New System.Drawing.Size(44, 13)
        Me.lblClients.TabIndex = 0
        Me.lblClients.Text = "Clients:"
        '
        'dsMaster1
        '
        Me.dsMaster1.DataSetName = "dsMaster"
        Me.dsMaster1.Locale = New System.Globalization.CultureInfo("en-US")
        Me.dsMaster1.Namespace = "http://www.tempuri.org/dsMaster.xsd"
        '
        'btnTable
        '
        Me.btnTable.Location = New System.Drawing.Point(416, 24)
        Me.btnTable.Name = "btnTable"
        Me.btnTable.Size = New System.Drawing.Size(96, 24)
        Me.btnTable.TabIndex = 5
        Me.btnTable.Text = "Add Table"
        '
        'frmDataSets
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(520, 373)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.btnTable, Me.btnSelect, Me.btnUnique, Me.btnForeign, Me.btnSchema, Me.btnVersion, Me.btnAddRow, Me.btnCalculate, Me.btnDataSet, Me.dgOrders, Me.lbClients, Me.lbEmployees, Me.lblOrders, Me.lblClients, Me.lblEmployees})
        Me.Name = "frmDataSets"
        Me.Text = "DataTables"
        CType(Me.dtChild, System.ComponentModel.ISupportInitialize).EndInit()
        CType(Me.dsUntyped, System.ComponentModel.ISupportInitialize).EndInit()
        CType(Me.dtMaster, System.ComponentModel.ISupportInitialize).EndInit()
        CType(Me.dgOrders, System.ComponentModel.ISupportInitialize).EndInit()
        CType(Me.dsMaster1, System.ComponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub btnTable_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTable.Click
        Dim strMessage As String

        'Create the table
        Dim dtEmployees As New System.Data.DataTable("Employees")

        strMessage = "The table name is "
        strMessage &= dtEmployees.TableName.ToString
        MessageBox.Show(strMessage)
    End Sub

    Private Sub btnDataSet_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnDataSet.Click
        Dim strMessage As String

        'Create the table
        Me.dsEmployees.Tables.Add()

        strMessage = "The table name is "
        strMessage &= Me.dsEmployees.Tables(0).TableName.ToString
        MessageBox.Show(strMessage)
    End Sub

    Private Sub btnSchema_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSchema.Click
        Dim strMessage As String

        Me.dsEmployees.Tables.Add("Employees")
        Me.daEmployees.FillSchema(Me.dsEmployees.Tables("Employees"), _
           SchemaType.Source)

        With Me.dsEmployees.Tables("Employees")
            strMessage = "Primary Key:  "
            strMessage &= .PrimaryKey(0).ColumnName.ToString
            strMessage &= vbCrLf & "Constraint Count:  "
            strMessage &= .Constraints(0).ConstraintName.ToString
            MessageBox.Show(strMessage)
        End With
    End Sub

    Private Sub btnCalculate_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
        Dim dcName As System.Data.DataColumn

        'Create the table
        Me.dsEmployees.Tables.Add("Employees")

        'Fill the table from daEmployees
        Me.daEmployees.Fill(Me.dsEmployees.Tables(0))

        'Create the column
        dcName = New System.Data.DataColumn("Name")
        dcName.DataType = System.Type.GetType("System.String")
        dcName.Expression = "FirstName + ' ' + LastName"

        'Add the calculated column
        Me.dsEmployees.Tables("Employees").Columns.Add(dcName)

        'Bind to the listbox
        Me.lbEmployees.DataSource = Me.dsEmployees.Tables("Employees")
        Me.lbEmployees.DisplayMember = "Name"

    End Sub

    Private Sub btnAddRow_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAddRow.Click
        Dim drNew As System.Data.DataRow

        'Create the new row
        drNew = Me.dsMaster1.CustomerList.NewRow
        drNew.Item("CustomerID") = "ANEWR"
        drNew.Item("CompanyName") = "A New Row"

        'Add row to table
        Me.dsMaster1.CustomerList.Rows.Add(drNew)

        'Refresh the display
        Me.lbClients.Refresh()
    End Sub

    Private Sub btnVersion_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnVersion.Click
        Dim strMessage As String

        With Me.dsMaster1.CustomerList.Rows(0)
            .Item("CustomerID") = "NEWVAL"
            strMessage = "The RowState is " & .RowState.ToString
            strMessage &= vbCrLf & "The original value was "
            strMessage &= .Item("CustomerID", DataRowVersion.Original)
            strMessage &= vbCrLf & "The new value is "
            strMessage &= .Item("CustomerID", DataRowVersion.Current)
        End With

        MessageBox.Show(strMessage)
    End Sub

    Private Sub btnForeign_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnForeign.Click
        Dim strMessage As String
        Dim fkNew As System.Data.ForeignKeyConstraint

        With Me.dsUntyped
            fkNew = New System.Data.ForeignKeyConstraint("NewFK", _
                    .Tables("dtMaster").Columns("MasterID"), _
                    .Tables("dtChild").Columns("MasterLink"))
            .Tables("dtChild").Constraints.Add(fkNew)

            strMessage = "The new constraint is called "
            strMessage &= .Tables("dtChild").Constraints(0).ConstraintName.ToString
        End With

        MessageBox.Show(strMessage)
    End Sub

    Private Sub btnUnique_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnUnique.Click
        Dim strMessage As String
        Dim ucNew As System.Data.UniqueConstraint

        With Me.dsUntyped.Tables("dtMaster")
            ucNew = New System.Data.UniqueConstraint("NewUnique", _
                .Columns("MasterValue"))
            .Constraints.Add(ucNew)

            strMessage = "The new constraint is called "
            strMessage &= .Constraints("NewUnique").ConstraintName.ToString
        End With

        MessageBox.Show(strMessage)
    End Sub

    Private Sub btnSelect_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSelect.Click
        Dim drFound() As System.Data.DataRow
        Dim dr As System.Data.DataRow

        drFound = Me.dsMaster1.CustomerList.Select("CustomerID LIKE 'A*'")

        Me.lbClients.DataSource = Nothing
        Me.lbClients.Items.Clear()

        For Each dr In drFound
            Me.lbClients.Items.Add(dr("CompanyName"))
        Next

        Me.lbClients.Refresh()
    End Sub

    Private Sub lbClients_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lbClients.SelectedIndexChanged
        Dim drCurrent As System.Data.DataRow
        Dim dsCustOrders As New System.Data.DataSet()
        Dim drCustOrders() As System.Data.DataRow

        'Create the relation if necessary
        If Me.dsMaster1.Relations.Count = 0 Then
            Me.dsMaster1.Relations.Add("CustomerOrders", _
               Me.dsMaster1.CustomerList.CustomerIDColumn, _
               Me.dsMaster1.OrderTotals.CustomerIDColumn)
        End If

        drCurrent = Me.lbClients.SelectedItem.Row
        dsCustOrders.Merge(drCurrent.GetChildRows("CustomerOrders"))

        Me.dgOrders.SetDataBinding(dsCustOrders, "OrderTotals")
        Me.dgOrders.Refresh()
    End Sub
End Class