VB.Net Tutorial/Database ADO.net/DataTable — различия между версиями
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Текущая версия на 15:56, 26 мая 2010
Filter DataTable by a logic condition
<source lang="vbnet">Imports System.Windows.Forms Imports System.Data Imports System.Data.OleDb public class CreateDataTableAndFilteredByLogicCondition
public Shared Sub Main Application.Run(New Form1) End Sub
End class
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load Dim contacts_table As New DataTable("Contacts") " Add columns. contacts_table.Columns.Add("FirstName", GetType(String)) contacts_table.Columns.Add("LastName", GetType(String)) contacts_table.Columns.Add("Street", GetType(String)) contacts_table.Columns.Add("City", GetType(String)) contacts_table.Columns.Add("State", GetType(String)) contacts_table.Columns.Add("Zip", GetType(String)) contacts_table.Rows.Add(New Object() {"A", "A", _ "1234", "B", "A", "11111"}) contacts_table.Rows.Add(New Object() {"B", "B", _ "22", "B", "C", "22222"}) contacts_table.Rows.Add(New Object() {"C", "C", _ "3", "P", "K", "33333"}) contacts_table.Rows.Add(New Object() {"", "D", _ "4", "P", "KS", "44444"}) grdAll.DataSource = contacts_table grdAll.CaptionText = "All Records" Dim dv_name As New DataView(contacts_table) dv_name.RowFilter = "FirstName >= "A"" grdName.DataSource = dv_name grdName.CaptionText = "LastName >= E" End Sub
End Class <Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _ Partial Public Class Form1
Inherits System.Windows.Forms.Form "Form overrides dispose to clean up the component list. <System.Diagnostics.DebuggerNonUserCode()> _ Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean) If disposing AndAlso components IsNot Nothing Then components.Dispose() End If MyBase.Dispose(disposing) End Sub "Required by the Windows Form Designer Private components As System.ruponentModel.IContainer "NOTE: The following procedure is required by the Windows Form Designer "It can be modified using the Windows Form Designer. "Do not modify it using the code editor. <System.Diagnostics.DebuggerStepThrough()> _ Private Sub InitializeComponent() Me.SplitContainer1 = New System.Windows.Forms.SplitContainer Me.SplitContainer2 = New System.Windows.Forms.SplitContainer Me.grdAll = New System.Windows.Forms.DataGrid Me.grdCO = New System.Windows.Forms.DataGrid Me.grdName = New System.Windows.Forms.DataGrid Me.SplitContainer1.Panel1.SuspendLayout() Me.SplitContainer1.Panel2.SuspendLayout() Me.SplitContainer1.SuspendLayout() Me.SplitContainer2.Panel1.SuspendLayout() Me.SplitContainer2.Panel2.SuspendLayout() Me.SplitContainer2.SuspendLayout() CType(Me.grdAll, System.ruponentModel.ISupportInitialize).BeginInit() CType(Me.grdCO, System.ruponentModel.ISupportInitialize).BeginInit() CType(Me.grdName, System.ruponentModel.ISupportInitialize).BeginInit() Me.SuspendLayout() " "SplitContainer1 " Me.SplitContainer1.Dock = System.Windows.Forms.DockStyle.Fill Me.SplitContainer1.Location = New System.Drawing.Point(0, 0) Me.SplitContainer1.Name = "SplitContainer1" Me.SplitContainer1.Orientation = System.Windows.Forms.Orientation.Horizontal " "SplitContainer1.Panel1 " Me.SplitContainer1.Panel1.Controls.Add(Me.grdAll) " "SplitContainer1.Panel2 " Me.SplitContainer1.Panel2.Controls.Add(Me.SplitContainer2) Me.SplitContainer1.Size = New System.Drawing.Size(519, 485) Me.SplitContainer1.SplitterDistance = 180 Me.SplitContainer1.TabIndex = 2 Me.SplitContainer1.Text = "SplitContainer1" " "SplitContainer2 " Me.SplitContainer2.Dock = System.Windows.Forms.DockStyle.Fill Me.SplitContainer2.Location = New System.Drawing.Point(0, 0) Me.SplitContainer2.Name = "SplitContainer2" Me.SplitContainer2.Orientation = System.Windows.Forms.Orientation.Horizontal " "SplitContainer2.Panel1 " Me.SplitContainer2.Panel1.Controls.Add(Me.grdCO) " "SplitContainer2.Panel2 " Me.SplitContainer2.Panel2.Controls.Add(Me.grdName) Me.SplitContainer2.Size = New System.Drawing.Size(519, 301) Me.SplitContainer2.SplitterDistance = 173 Me.SplitContainer2.TabIndex = 0 Me.SplitContainer2.Text = "SplitContainer2" " "grdAll " Me.grdAll.DataMember = "" Me.grdAll.Dock = System.Windows.Forms.DockStyle.Fill Me.grdAll.HeaderForeColor = System.Drawing.SystemColors.ControlText Me.grdAll.Location = New System.Drawing.Point(0, 0) Me.grdAll.Name = "grdAll" Me.grdAll.Size = New System.Drawing.Size(519, 180) Me.grdAll.TabIndex = 0 " "grdCO " Me.grdCO.DataMember = "" Me.grdCO.Dock = System.Windows.Forms.DockStyle.Fill Me.grdCO.HeaderForeColor = System.Drawing.SystemColors.ControlText Me.grdCO.Location = New System.Drawing.Point(0, 0) Me.grdCO.Name = "grdCO" Me.grdCO.Size = New System.Drawing.Size(519, 173) Me.grdCO.TabIndex = 1 " "grdName " Me.grdName.DataMember = "" Me.grdName.Dock = System.Windows.Forms.DockStyle.Fill Me.grdName.HeaderForeColor = System.Drawing.SystemColors.ControlText Me.grdName.Location = New System.Drawing.Point(0, 0) Me.grdName.Name = "grdName" Me.grdName.Size = New System.Drawing.Size(519, 124) Me.grdName.TabIndex = 1 " "Form1 " Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!) Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font Me.ClientSize = New System.Drawing.Size(519, 485) Me.Controls.Add(Me.SplitContainer1) Me.Name = "Form1" Me.Text = "Contacts" Me.SplitContainer1.Panel1.ResumeLayout(False) Me.SplitContainer1.Panel2.ResumeLayout(False) Me.SplitContainer1.ResumeLayout(False) Me.SplitContainer2.Panel1.ResumeLayout(False) Me.SplitContainer2.Panel2.ResumeLayout(False) Me.SplitContainer2.ResumeLayout(False) CType(Me.grdAll, System.ruponentModel.ISupportInitialize).EndInit() CType(Me.grdCO, System.ruponentModel.ISupportInitialize).EndInit() CType(Me.grdName, System.ruponentModel.ISupportInitialize).EndInit() Me.ResumeLayout(False) End Sub Friend WithEvents SplitContainer1 As System.Windows.Forms.SplitContainer Friend WithEvents grdAll As System.Windows.Forms.DataGrid Friend WithEvents SplitContainer2 As System.Windows.Forms.SplitContainer Friend WithEvents grdCO As System.Windows.Forms.DataGrid Friend WithEvents grdName As System.Windows.Forms.DataGrid
End Class</source>
Output data in DataTable to XML file
<source lang="vbnet">Imports System.Data Imports System.Data.OleDb Imports System.IO Imports System.Windows.Forms public class DataTableToXML
public Shared Sub Main Application.Run(New Form1) End Sub
End class
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load Dim scores_dataset As New DataSet("Scores") Dim students_table As DataTable = scores_dataset.Tables.Add("Students") students_table.Columns.Add("FirstName", GetType(String)) students_table.Columns.Add("LastName", GetType(String)) students_table.Columns.Add("StudentId", GetType(Integer)) students_table.Columns("StudentId").Unique = True Dim first_last_columns() As DataColumn = { _ students_table.Columns("FirstName"), _ students_table.Columns("LastName") _ } students_table.Constraints.Add( _ New UniqueConstraint(first_last_columns)) " Make the TestScores table. Dim test_scores_table As DataTable = _ scores_dataset.Tables.Add("TestScores") " Add columns to the TestScores table. test_scores_table.Columns.Add("StudentId", GetType(Integer)) test_scores_table.Columns.Add("TestNumber", GetType(Integer)) test_scores_table.Columns.Add("Score", GetType(Integer)) " Make the combined StudentId/TestNumber unique. Dim studentid_testnumber_score_columns() As DataColumn = { _ test_scores_table.Columns("StudentId"), _ test_scores_table.Columns("TestNumber") _ } test_scores_table.Constraints.Add( _ New UniqueConstraint(studentid_testnumber_score_columns)) " Make a relationship linking the " two tables" StudentId fields. scores_dataset.Relations.Add( _ "Student Test Scores", _ students_table.Columns("StudentId"), _ test_scores_table.Columns("StudentId")) " Make some student data. students_table.Rows.Add(New Object() {"A", "A", 1}) students_table.Rows.Add(New Object() {"B", "B", 2}) students_table.Rows.Add(New Object() {"C", "C", 3}) students_table.Rows.Add(New Object() {"D", "D", 4}) " Make some random test scores. Dim score As New Random For id As Integer = 1 To 4 For test_num As Integer = 1 To 10 test_scores_table.Rows.Add( _ New Object() {id, test_num, score.Next(65, 100)}) Next test_num Next id students_table.Columns("FirstName").ColumnMapping = MappingType.Element students_table.Columns("LastName").ColumnMapping = MappingType.Element students_table.Columns("StudentId").ColumnMapping = MappingType.Attribute Dim string_writer As New StringWriter() students_table.WriteXml(string_writer) Console.WriteLine(string_writer) grdScores.DataSource = scores_dataset End Sub
End Class <Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _ Partial Public Class Form1
Inherits System.Windows.Forms.Form "Form overrides dispose to clean up the component list. <System.Diagnostics.DebuggerNonUserCode()> _ Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean) If disposing AndAlso components IsNot Nothing Then components.Dispose() End If MyBase.Dispose(disposing) End Sub "Required by the Windows Form Designer Private components As System.ruponentModel.IContainer "NOTE: The following procedure is required by the Windows Form Designer "It can be modified using the Windows Form Designer. "Do not modify it using the code editor. <System.Diagnostics.DebuggerStepThrough()> _ Private Sub InitializeComponent() Me.grdScores = New System.Windows.Forms.DataGrid CType(Me.grdScores, System.ruponentModel.ISupportInitialize).BeginInit() Me.SuspendLayout() " "grdScores " Me.grdScores.DataMember = "" Me.grdScores.Dock = System.Windows.Forms.DockStyle.Fill Me.grdScores.HeaderForeColor = System.Drawing.SystemColors.ControlText Me.grdScores.Location = New System.Drawing.Point(0, 0) Me.grdScores.Name = "grdScores" Me.grdScores.Size = New System.Drawing.Size(292, 273) Me.grdScores.TabIndex = 1 " "Form1 " Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!) Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font Me.ClientSize = New System.Drawing.Size(292, 273) Me.Controls.Add(Me.grdScores) Me.Name = "Form1" Me.Text = "MemoryDataSet" CType(Me.grdScores, System.ruponentModel.ISupportInitialize).EndInit() Me.ResumeLayout(False) End Sub Friend WithEvents grdScores As System.Windows.Forms.DataGrid
End Class</source>