引入数据库操作类命名空间.doc

Imports System.Data 引入数据库操作类命名空间Imports System.Data.OleDb 引入ADO.NET操作命名空间Public Class Form2 Dim objConn As New OleDb.OleDbConnection 创建一个连接对象 Dim objDa As New OleDb.OleDbDataAdapter 创建一个OleDbDataAdapter对象 Dim objComm As New OleDb.OleDbCommand 创建一个OleDbCommand对象 Dim objDs As New DataSet 创建一个数据集DataSet对象 Dim mytable As Data.DataTable 建立表单对象 Dim myrow As Data.DataRow 建立数据行对象 Dim mycol As Data.DataColumn 建立数据列对象 Dim rownumber As Integer 定义一个整型变量来存放当前行数 Dim sqlSTR As String 定义一个文本型变量，用于存放SQL命令 Private Sub Form2_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed objConn.Close() 关闭数据库连接 End Sub Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim i As Integer objConn.ConnectionString = Provider=Microsoft.Jet.OLEDB.4.0;Data Source=e:VBnet练习dbgl.mdb 设置连接字符串 objComm.CommandText = select * from 学生表 设置SQL命令，告诉程序如何获取数据 objComm.Connection = objConn objDa.SelectCommand = objComm objConn.Open() 打开数据库连接 objDa.Fill(objDs) 填充数据集对象objDa mytable = objDs.Tables.Item(0) 取得名为table的表 ShowData() 显示记录 txtXh.Enabled = False 设置学号文本框无效 For i = 0 To mytable.Columns.Count - 1 将字段名添加到组合匡中 mycol = mytable.Columns(i) cmbSelStr1.Items.Add(mycol.ColumnName) Next cmbSelStr1.Text = mytable.Columns(0).ColumnName 使组合框首先显示第一个字段名 End Sub Private Sub ShowData() 自定义过程，用于显示当前记录 If mytable.Rows.Count = 0 Then LabCount.Text = (无记录) txtXh.Text = txtXm.Text = txtCsrq.Text = txtJtzz.Text = Else myrow = mytable.Rows.Item(rownumber) 从表对象中取出数据赋值给窗体上的文本框 txtXh.Text = myrow.Item(0).ToString txtXm.Text = myrow.Item(1).ToString txtCsrq.Text = myrow.Item(2).ToString txtJtzz.Text = myrow.Item(3).ToString LabCount.Text = rownumber + 1 & / & mytable.Rows.Count 显示计数器 End If End Sub Private Sub btnNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNext.Click 指向下一条数据 btnPrev.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 btnNext.Enabled = False End If ShowData() End Sub Private Sub btnPrev_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPrev.Click 指向上一条数据 btnNext.Enabled = True rownumber = rownumber - 1 If rownumber mytable.Rows.Count - 1 Then 判断是否删除的是最后一条数据 rownumber = mytable.Rows.Count - 1 End If MsgBox(数据库记录已经删除完毕!, 48, 系统提示) Else MsgBox(你没有选择任何操作功能，请先选择功能, vbOKOnly + vbCritical, 系统警告信息) End If ShowData() 显示记录 End Sub Private Sub btnsel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsel.Click End Sub Private Sub rdUp_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles rdUp.Click 选择修改功能时，将已做修改作废，重新读取记录数据，并禁止修改学号 ShowData() 显示记录 txtXh.Enabled = False 设置学号文本框无效 End Sub Private Sub rdIns_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)