Imports System.Data
Imports System.Data.OleDb
'引入ADO.NET *** 作命名空间
Public Class FrmModifystInfo
Inherits System.Windows.Forms.Form
Public ADOcmd As OleDbDataAdapter
Public ds As DataSet = New DataSet()
'建立DataSet对象
Public mytable As Data.DataTable
'建立表单对象
Public myrow As Data.DataRow
'建立数据行对象
Public rownumber As Integer
'定义一个整型变量来存放当前行数
Public SearchSQL As String
Public cmd As OleDbCommandBuilder
'======================================================
#Region " Windows 窗体设计器生成的代码 "
#End Region
'======================================================
Private Sub FrmModifystInfo_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
'窗体的载入
TxtSID.Enabled = False
TxtName.Enabled = False
ComboSex.Enabled = False
TxtBornDate.Enabled = False
TxtClassno.Enabled = False
TxtRuDate.Enabled = False
TxtTel.Enabled = False
TxtAddress.Enabled = False
TxtComment.Enabled = False '设置信息为只读
Dim tablename As String = "student_Info "
SearchSQL = "select * from student_Info "
ExecuteSQL(SearchSQL, tablename) '打开数据库
ShowData() '显示记录
End Sub
Private Sub ShowData()
'在窗口中的textbox中显示数据
myrow = mytable.Rows.Item(rownumber)
TxtSID.Text = myrow.Item(0).ToString
TxtName.Text = myrow.Item(1).ToString
ComboSex.Text = myrow.Item(2).ToString
TxtBornDate.Text = Format(myrow.Item(3), "yyyy-MM-dd ")
TxtClassno.Text = myrow.Item(4).ToString
TxtTel.Text = myrow.Item(5).ToString
TxtRuDate.Text = Format(CDate(myrow.Item(6)), "yyyy-MM-dd ")
TxtAddress.Text = myrow.Item(7).ToString
TxtComment.Text = myrow.Item(8).ToString
End Sub
Private Sub BtFirst_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtFirst.Click
'指向第一条数据
rownumber = 0
ShowData()
End Sub
Private Sub BtPrev_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtPrev.Click
'指向上一条数据
BtNext.Enabled = True
rownumber = rownumber - 1
If rownumber < 0 Then
rownumber = 0 '如果到达记录的首部，行号设为零
BtPrev.Enabled = False
End If
ShowData()
End Sub
Private Sub BtNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtNext.Click
'指向上一条数据
BtPrev.Enabled = True
rownumber = rownumber + 1
If rownumber > mytable.Rows.Count - 1 Then
rownumber = mytable.Rows.Count - 1 '判断是否到达最后一条数据
BtNext.Enabled = False
End If
ShowData()
End Sub
Private Sub BtLast_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtLast.Click
'指向最后一条数据
rownumber = mytable.Rows.Count - 1
ShowData()
End Sub
Private Sub BtDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtDelete.Click
mytable.Rows.Item(rownumber).Delete() '删除记录
If MsgBox( "确定要删除改记录吗？ ", MsgBoxStyle.OKCancel + vbExclamation, "警告 ") = MsgBoxResult.OK Then
cmd = New OleDbCommandBuilder(ADOcmd)
'使用自动生成的SQL语句
ADOcmd.Update(ds, "student_Info ")
BtNext.PerformClick()
End If
End Sub
Private Sub BtModify_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtModify.Click
TxtSID.Enabled = False '关键字段只读
TxtName.Enabled = True '可读写
ComboSex.Enabled = True
TxtBornDate.Enabled = True
TxtClassno.Enabled = True
TxtRuDate.Enabled = True
TxtTel.Enabled = True
TxtAddress.Enabled = True
TxtComment.Enabled = True
End Sub
Private Sub BtUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtUpdate.Click
If Not Testtxt(TxtName.Text) Then
MsgBox( "请输入姓名！ ", vbOKOnly + vbExclamation, "警告 ")
TxtName.Focus()
Exit Sub
End If
If Not Testtxt(ComboSex.Text) Then
MsgBox( "请选择性别！ ", vbOKOnly + vbExclamation, "警告 ")
ComboSex.Focus()
Exit Sub
End If
If Not Testtxt(TxtClassno.Text) Then
MsgBox( "请选择班号！ ", vbOKOnly + vbExclamation, "警告 ")
TxtClassno.Focus()
Exit Sub
End If
If Not Testtxt(TxtTel.Text) Then
MsgBox( "请输入联系电话！ ", vbOKOnly + vbExclamation, "警告 ")
TxtTel.Focus()
Exit Sub
End If
If Not Testtxt(TxtAddress.Text) Then
MsgBox( "请输入家庭住址！ ", vbOKOnly + vbExclamation, "警告 ")
TxtAddress.Focus()
Exit Sub
End If
If Not IsNumeric(Trim(TxtSID.Text)) Then
MsgBox( "请输入数字学号！ ", vbOKOnly + vbExclamation, "警告 ")
Exit Sub
TxtSID.Focus()
End If
If Not IsDate(TxtBornDate.Text) Then
MsgBox( "出生时间应输入日期格式（yyyy-mm-dd）！ ", vbOKOnly + vbExclamation, "警告 ")
Exit Sub
TxtBornDate.Focus()
End If
If Not IsDate(TxtRuDate.Text) Then
MsgBox( "入校时间应输入日期格式（yyyy-mm-dd）！ ", vbOKOnly + vbExclamation, "警告 ")
TxtRuDate.Focus()
Exit Sub
End If
myrow.Item(0) = Trim(TxtSID.Text)
myrow.Item(1) = Trim(TxtName.Text)
myrow.Item(2) = Trim(ComboSex.Text)
myrow.Item(3) = Trim(TxtBornDate.Text)
myrow.Item(4) = Trim(TxtClassno.Text)
myrow.Item(5) = Trim(TxtTel.Text)
myrow.Item(6) = Trim(TxtRuDate.Text)
myrow.Item(7) = Trim(TxtAddress.Text)
myrow.Item(8) = Trim(TxtComment.Text)
mytable.GetChanges()
cmd = New OleDbCommandBuilder(ADOcmd)
'使用自动生成的SQL语句
ADOcmd.Update(ds, "student_Info ")
'对数据库进行更新
MsgBox( "修改学籍信息成功！ ", vbOKOnly + vbExclamation, "警告 ")
TxtName.Enabled = False
ComboSex.Enabled = False
TxtBornDate.Enabled = False
TxtClassno.Enabled = False
TxtRuDate.Enabled = False
TxtTel.Enabled = False
TxtAddress.Enabled = False
TxtComment.Enabled = False '重新设置信息为只读
End Sub
Private Sub BtCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtCancel.Click
TxtSID.Enabled = False
TxtName.Enabled = False
ComboSex.Enabled = False
TxtBornDate.Enabled = False
TxtClassno.Enabled = False
TxtRuDate.Enabled = False
TxtTel.Enabled = False
TxtAddress.Enabled = False
TxtComment.Enabled = False
End Sub
Public Function ExecuteSQL(ByVal SQL As String, ByVal table As String)
Try
'建立ADODataSetCommand对象
'数据库查询函数
ADOcmd = New OleDbDataAdapter(SQL, "Provider=Microsoft.Jet.OLEDB.4.0Data Source=c:\student.mdb ")
'建立ADODataSetCommand对象
ADOcmd.Fill(ds, table) '取得表单
mytable = ds.Tables.Item(0) '取得名为table的表
rownumber = 0 '设置为第一行
myrow = mytable.Rows.Item(rownumber)
'取得第一行数据
Catch
MsgBox(Err.Description)
End Try
End Function
End Class
如果楼主熟悉VB6，可以直接在项目中添加ADODB的Com引用，这样你就可以像VB6那样 *** 作数据库了！另外
.NET
Framework中连接数据库要用到ADO.NET。如果要 *** 作Access数据库，要用到System.Data.OleDb命名空间下的许多类。
比如按楼主所说，“我想在textbox1中显示表一中【一些数据】字段下的第一个内容”：
'首先导入命名空间
Imports
System.Data
Imports
System.Data.OleDb
'然后在某一个事件处理程序中写：
Dim
conn
As
New
OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0Data
Source=数据库.accdbJet
OLEDB:Database
Password=MyDbPassword")
Dim
command
As
New
OleDbCommand("Select
*
From
数据表",
conn)
conn.Open()
'打开数据库连接
Dim
reader
As
OleDbDataReader
=
command.ExecuteReader()
'执行SQL语句，返回OleDbDataReader
对象
Do
While
reader.Read()
'读取一条数据
textbox1.Text
+=
reader("一些数据")
&
VbCrLf
Loop
reader.Close()
'关闭OleDbDataReader
conn.Close()
'关闭连接
分类: 电脑/网络 >>程序设计 >>其他编程语言解析:
Visual Basic.NET快速开发MIS系统
【摘 要】 本文介绍微软最新技术Visual Basic.NET在数据库开发方面的应用。结合数据库系统开发的知识，介绍了物理表 *** 作的方法，利用Visual Basic.NET的面向对象的特征，利用类的继承知识，简化了数据库系统开发过程。
引言
以前版本的Visual Basic虽然号称自己是一种OOP（面向对象）编程语言，但却不是一个地地道道的OOP编程语言，最多只是半个面向对象的编程语言。但Visual Basic.NET已经是一种完全的面向对象的编程语言。他支持面向对象的所有基本特征：继承、多态和重载。这使得以前在Visual Basic中很难或根本实现不了的问题，在Visual Basic.NET中可以顺利的用简单的方法实现。
自定义数据 *** 作类
定义一个数据访问的基类，并编写有关数据库 *** 作的必要方法。
定义一个数据访问类，类名为CData。定义连接Oracle数据库的方法ConnOracle，获取数据集的方法GetDataSet, 获取物理表的方法GetDataTable, 向物理表中插入一行数据的方法Insert, 向物理表中删除数据的方法Delete, 向物理表中更新数据的方法Update。其实现方法不是本文的重点，在此仅给出代码，不作详细分析。代码如下：
Public Class CDataBase
Dim OleCnnDB As New OleDbConnection()
@#连接Oracle数据库，ServerName:服务器名，UserId:用户名，UserPwd:用户密码
Public Function ConnOracle(ByVal ServerName As String, ByVal UserId As String, ByVal UserPwd As String) As OleDbConnection
Dim OleCnnDB As New OleDbConnection()
With OleCnnDB
.ConnectionString = "Provider=MSDAORA.1Password=@#" &UserPwd &"@#User ID=@#" &UserId &"@#Data Source=@#" &ServerName &"@#"
Try
.Open()
Catch er As Exception
MsgBox(er.ToString)
End Try
End With
mOleCnnDB = OleCnnDB
Return OleCnnDB
End Function
@#获取数据集。TableName：表名，strWhere：条件
Public Overloads Function GetDataSet(ByVal TableName As String, ByVal strWhere As String) As DataSet
Dim strSql As String
Dim myDataSet As New DataSet()
Dim myOleDataAdapter As New OleDbDataAdapter()
myOleDataAdapter.TableMappings.Add(TableName, TableName)
strSql = "SELECT * FROM " &TableName &" where " &strWhere
myOleDataAdapter.SelectCommand = New OleDbCommand(strSql, mOleCnnDB)
Try
myOleDataAdapter.Fill(myDataSet)
Catch er As Exception
MsgBox(er.ToString)
End Try
Return myDataSet
End Function
@#获取物理表。TableName：表名
Public Overloads Function GetDataTable(ByVal TableName As String) As DataTable
Dim myDataSet As New DataSet()
myDataSet = GetDataSet(TableName)
Return myDataSet.Tables(0)
End Function
@#获取物理表。TableName：表名，strWhere：条件
Public Overloads Function GetDataTable(ByVal TableName As String, ByVal strWhere As String) As DataTable
Dim myDataSet As New DataSet()
myDataSet = GetDataSet(TableName, strWhere)
Return myDataSet.Tables(0)
End Function
@#向物理表中插入一行数据。TableName：表名，Value：行数据，BeginColumnIndex：开始列
Public Overloads Function Insert(ByVal TableName As String, ByVal Value As Object, Optional ByVal BeginColumnIndex As Int16 = 0) As Boolean
Dim myDataAdapter As New OleDbDataAdapter()
Dim strSql As String
Dim myDataSet As New DataSet()
Dim dRow As DataRow
Dim i, len As Int16
strSql = "SELECT * FROM " &TableName
myDataAdapter.SelectCommand = New OleDbCommand(strSql, mOleCnnDB)
Dim custCB As OleDbCommandBuilder = New OleDbCommandBuilder(myDataAdapter)
myDataSet.Tables.Add(TableName)
myDataAdapter.Fill(myDataSet, TableName)
dRow = myDataSet.Tables(TableName).NewRow
len = Value.Length
For i = BeginColumnIndex To len - 1
If Not (IsDBNull(Value(i)) Or IsNothing(Value(i))) Then
dRow.Item(i) = Value(i)
End If
Next
myDataSet.Tables(TableName).Rows.Add(dRow)
Try
myDataAdapter.Update(myDataSet, TableName)
Catch er As Exception
MsgBox(er.ToString)
Return False
End Try
myDataSet.Tables.Remove(TableName)
Return True
End Function
@#更新物理表的一个字段的值。strSql：查询语句，FieldName_Value：字段及与对应的值
Public Overloads Sub Update(ByVal strSql As String, ByVal FieldName_Value As String)
Dim myDataAdapter As New OleDbDataAdapter()
Dim myDataSet As New DataSet()
Dim dRow As DataRow
Dim TableName, FieldName As String
Dim Value As Object
Dim a() As String
a = strSql.Split(" ")
TableName = a(3)
a = FieldName_Value.Split("=")
FieldName = a(0).Trim
Value = a(1)
myDataAdapter.SelectCommand = New OleDbCommand(strSql, mOleCnnDB)
Dim custCB As OleDbCommandBuilder = New OleDbCommandBuilder(myDataAdapter)
myDataSet.Tables.Add(TableName)
myDataAdapter.Fill(myDataSet, TableName)
dRow = myDataSet.Tables(TableName).Rows(0)
If Value <>Nothing Then
dRow.Item(FieldName) = Value
End If
Try
myDataAdapter.Update(myDataSet, TableName)
myDataSet.Tables.Remove(TableName)
Catch er As Exception
MsgBox(er.ToString)
End Try
End Sub
@#删除物理表的数据。TableName:表名，strWhere：条件
Public Overloads Sub Delete(ByVal TableName As String, ByVal strWhere As String)
Dim myReader As OleDbDataReader
Dim myCommand As New OleDbCommand()
Dim strSql As String
strSql = "delete FROM " &TableName &" where " &strWhere
myCommand.Connection = mOleCnnDB
myCommand.CommandText = strSql
Try
myReader = myCommand.ExecuteReader()
myReader.Close()
Catch er As Exception
MsgBox(er.ToString)
End Try
End Sub
End Class
定义一 *** 作数据库中物理表的类CData,此类继承CDataBase,即：
Public Class CData：Inherits CDataBase
此类应该由供用户提供所 *** 作的物理表的表名，指定了表名就可取得该表的所有性质。该表主要完成插入、删除、更新功能。定义其属性、方法如下：
申明类CData的变量:
@#所要 *** 作的表名
Private Shared UpdateTableName As String
@#所要 *** 作的表对象
Public Shared UpdateDataTable As New DataTable()
@#对应表的一行数据197
Public Shared ObjFields() As Object
@#表的字段数
Public Shared FieldCount As Int16
@#主关键字。我们假设每个物理表都有一个主关键字字段fSystemID
Public Shared SystemID As String
说明：Shared 关键字指示一个或多个被声明的编程元素将被共享。共享元素不关联于某类或结构的特定实例。可以通过使用类名或结构名称或者类或结构的特定实例的变量名称限定共享元素来访问它们。
申明类CData的属性UpdateTable,当向UpdateTable赋给了一个已知表的表名，就可确定表的字段数，定义出数据行。这里，先打开表，再重新定义数据行.
Public Property UpdateTable() As String
Get
UpdateTable = UpdateTableName
End Get
Set(ByVal Value As String)
UpdateTableName = Value.Trim
UpdateDataTable = DB.GetDataTable(UpdateTableName)
UpdateTableFieldNames = UpdateDataTable.Clone
FieldCount = UpdateDataTable.Columns.Count
ReDim ObjFields(FieldCount - 1)
End Set
End Property
@#删除由主关键值fSystemID指定的数据行
Public Sub Delete()
Dim strSQL As String
strSQL = "Delete from " &UpdateTableName &" where fSystemID=" &SystemID
DB.Delete(strSQL)
UpdateDataTable.Rows.Remove(GetRow)
End Sub
@#向表UpdateTableName中插入一行数据。数据由ObjFields给出
Public Function Insert() As Boolean
DB.Insert(UpdateTableName, ObjFields)
End Function
@#更新表UpdateTableName所指定的行
Public Shadows Sub Update()
Dim SetField As String
Dim i As Int16
For i = 1 To FieldCount - 1
SetField = UpdateTableFieldNames.Columns(i).ColumnName &"=" &ObjFields(i)
UpdateField(SetField)
Next
End Sub
Public Sub UpdateField(ByVal SetField As String)
Dim StrSQL As String
StrSQL = "select * from " &UpdateTableName &" where fSystemID= " &SystemID
DB.Update(StrSQL, SetField)
End Sub
@#填充网络数据
Public Overloads Sub FillGrid(ByVal GridName As DataGrid)
GridName.DataSource = UpdateDataTable
End Sub
@#把数据网格的当前行数据定写入到输入控件中
Public Sub DataGridToText(ByVal frm As Form)
Dim RowIndex, i As Int16
Dim value
Dim obj As Control
Dim DataGrid As New DataGrid()
If FieldCount = 0 Then Exit Sub
For Each obj In frm.Controls
If obj.GetType.Name = "DataGrid" Then
DataGrid = obj
Exit For
End If
Next
RowIndex = DataGrid.CurrentRowIndex
For i = 1 To FieldCount - 1
value = DataGrid.Item(RowIndex, i)
If IsDBNull(value) = True Then
value = ""
End If
For Each obj In frm.Controls @#
If obj.TabIndex = i Then
obj.Text = value
Exit For
End If
Next
Next
End Sub
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