网络应用与开发2

1、利用command对象的ExecuteScalar()方法读出Sample.mdb数据库中stu_info表的记录总数。

Imports System.Data

Imports ‘第一空

Private Sub insert_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles insert.Click

Dim objconn As New OleDbConnection ‘第二空

& Server.MapPath("sample.mdb") ‘第三空

‘第四空 Dim mySQL As String = "select count(*) from stu_info" Dim objCmd As New OleDbCommand(mySQL, objconn)

Dim totalrow As Integer = objCmd.ExecuteScalar() ‘第五空 Response.Write("记录总数为：" & totalrow) objconn.Close() End Sub

2、往sample.mdb数据库中stu_info表中插入一条记录，表中字段：学号、姓名、专业。

Imports System.Data

System.Data.OleDb ‘第一空

Private Sub insert_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles insert.Click

Dim objconn As New OleDbConnection ‘第二空

;Data source=" & Server.MapPath("sample.mdb") ‘第三空

objconn. ‘第四空 Dim mysql As String

mysql = "insert into stu_info(学号,姓名,专业) values('1001','王红','计算机应用')"

Dim objcmd As New OleDbCommand(mysql, objconn) ‘第五空 objconn.Close() Response.Write("一条记录插入成功") End Sub 3、用DataView对象象作为数据列表控件（DataGrid对象）的数据源，显示Sample.mdb数据库中Stu_info表的信息。

操作如下：添加Sample.mdb到项目中，插入DataGrid控件，属性均为默认，代码如

下：

Imports System.Data

Imports System.Data.OleDb

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load If Not Page.IsPostBack Then

Dim objconn As New OleDbConnection

objconn.ConnectionString = "Provider=Microsoft.JET.OLEDB.4.0;Data source=" & Server.MapPath("sample.mdb") Dim mysql As String

mysql = "select * from stu_info"

Dim myda As New OleDbDataAdapter (mysql, objconn) ‘第一空 '声明一个DataSet

Dim myds As New DataSet ‘第二空 '用DataAdapter的FILL方法填充DataSet myda.Fill(myds, "学生信息表") '定义DataView对象 Dim mydv As DataView

mydv = myds.Tables("学生信息表"). DefaultView ‘第三空

DataGrid1.DataSource = mydv ‘第四空 DataGrid1. DataBind() ‘第五空 End If End Sub

4、通过DataAdapter对象获取数据库Sample.mdb中表Stu_info中的记录，并填充到DataSet对象中。 Imports System.Data

Imports System.Data.OleDb

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.Then ‘第一空 Dim objconn As New OleDbConnection '设置链接字符串 objconn.ConnectionString = "Provider=Microsoft.JET.OLEDB.4.0;

Data source=" &Server.MapPath("sample.mdb")

‘第二空

Dim mysql As String

mysql = "select * from stu_info"