用绑定的方法可能会比较好解决

1、用sql语句就可以了吧
“select *  from 表  where   你的条件”
2、也可以用DataView来判断
Dim conn1 As New OleDbConnection
        Dim strString As String

strString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db.mdb;"  
        conn1 = New OleDbConnection(strString)

Dim myview As DataView = New DataView(DataSet31.chengji, "xingming='" & TextBox2.Text & "'", "xuehao", DataViewRowState.CurrentRows)
        Dim rowindex As Integer = myview.Find(TextBox1.Text)
        If rowindex = -1 Then
            Dim str As String = "insert into chengji(xuehao,xingming,kemubianhao,kemufenshu,banjimingcheng)values(@xuehao,@xingming,@kemubianhao,@kemufenshu,@banjimingcheng)"
            Dim com As OleDbCommand = New OleDbCommand(str, conn1)
            com.Parameters.Add("@xuehao", OleDbType.VarChar).Value = TextBox1.Text
            com.Parameters.Add("@xingming", OleDbType.VarChar).Value = TextBox2.Text
            com.Parameters.Add("@kemubianhao", OleDbType.VarChar).Value = ComboBox1.Text
            com.Parameters.Add("@kemufenshu", OleDbType.VarChar).Value = TextBox3.Text
            com.Parameters.Add("@banjimingcheng", OleDbType.VarChar).Value = ComboBox2.Text
            conn1.Open()
            com.ExecuteNonQuery()
            conn1.Close()
            MsgBox("you can")
        Else : MsgBox("you cannot")
        End If
        TextBox1.Text = ""
        TextBox2.Text = ""
        TextBox3.Text = ""  
        ComboBox1.Text = ""
        ComboBox2.Text = ""
(DataSet31是你绑定所连数据库表的数据集)

楼上,关于第一个问题,能说详细一点嘛?比如我想在一个表中随机选5个符合一定规则的记录,一定要是随机哦,应该怎么写代码,非常感谢

"select  top 5  字段 from 表名"
随机，俺就不晓得了。
抱歉！

top这个我知道,但是我现在想是随机选择~唉

太好了，我知道怎么弄了。
form1中拖过来一个Button 如下：
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim conn1 As New OleDbConnection
        Dim strString As String
        Dim cmd1 As OleDbCommand
        Dim s1 As String
        Dim dr1 As OleDbDataReader
        strString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db.mdb;"
        conn1 = New OleDbConnection(strString)
       conn1.Open()               
        Dim R As New Random
        Dim intRandomNumber As Integer
        intRandomNumber = R.Next(1, 1000)
        s1 = "select top 5 xuehao  from chengji Order By Rnd(" & (-1 * intRandomNumber).ToString() & " * xuehao)"
        cmd1 = New OleDbCommand(s1, conn1)
        dr1 = cmd1.ExecuteReader
        While dr1.Read
            MsgBox(dr1(0))
            ComboBox1.Items.Add(dr1(0))
        End While
        dr1.Close()
        conn1.Close()
你再试一下吧

不错不错，能解释一下关键部分吗？谢谢

由于Access数据库记录集缓存的原因，从代码里得到Access数据库随机记录是得不到，需要用随机SQL语句的办法来消除缓存。