vb.net 连接数据库及rs.MoveFirst() rs.MoveNext() rs.MoveLast() 用法

'登陆框
Public Class 登陆

Private Sub okbtn_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles okbtn.Click
If (Trim(usertext.Text) = "" Or Trim(passwordtext.Text) = "")

Then
MsgBox("用户名或密码不能为空", vbOKOnly, "提示") : Exit Sub
Else
Call connect()
End If
End Sub

Public Sub connect()
Dim pass As Boolean
pass = False
Dim conn As New ADODB.Connection
Dim rs As New ADODB.Recordset
Dim constr As String
Dim i As Integer
Dim sql As String
constr = "driver={SQL Server};server=PC-201105311336

\SQLEXPRESS;Uid=sa;Pwd=123456;Database=jiaxiaoai" '无源连接
'constr = "dsn=sqlserver;Uid=sa;Pwd=123456;Database=jiaxiaoai"

'有源连接
conn.Open(constr)
sql = "select * from sysname"
'rs.Open(sql, conn, ADODB.CursorTypeEnum.adOpenKeyset,

ADODB.LockTypeEnum.adLockReadOnly)
rs.Open(sql, conn, 1, 1)
If conn.State = 1 Then
For i = 1 To rs.RecordCount
If rs(0).Value = usertext.Text And rs(1).Value =

passwordtext.Text Then
pass = True
Else
If rs.EOF = True Then
Exit For
rs.MoveNext()
End If
End If
Next
If pass = True Then
Me.Hide()
显示学生信息.Show()'重点
Else
MsgBox("用户名或密码错误")
End If
Else
MsgBox("连接失败:state=" & conn.State)
End If

End Sub

Private Sub 登陆_Load(ByVal sender As Object, ByVal e As

System.EventArgs) Handles MyBase.Load
usertext.Text = ""
passwordtext.Text = ""
End Sub

Private Sub cancelbtn_Click(ByVal sender As System.Object, ByVal e

As System.EventArgs) Handles cancelbtn.Click
Close()

End Sub

End Class

'学生信息显示框
Public Class 显示学生信息
Dim rs As New ADODB.Recordset '定义一个全局变量

Public Sub connect()
Dim conn As New ADODB.Connection
Dim constr As String
Dim sql As String
constr = "driver={SQL Server};server=PC-201105311336

\SQLEXPRESS;Uid=sa;Pwd=123456;Database=jiaxiaoai" '无源连接
conn.Open(constr)
sql = "select * from student"
rs.Open(sql, conn, ADODB.CursorTypeEnum.adOpenKeyset,

ADODB.LockTypeEnum.adLockReadOnly)
End Sub

Private Sub firstbtn_Click(ByVal sender As System.Object, ByVal e

As System.EventArgs) Handles firstbtn.Click
rs.MoveFirst()
xuehaotext.Text = rs(0).Value
nametext.Text = rs(1).Value
sextext.Text = Str(rs(2).Value)
scoretext.Text = Str(rs(3).Value)
End Sub

Private Sub upbtn_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles upbtn.Click
rs.MovePrevious()
If rs.BOF = True Then
rs.MoveFirst()
End If
xuehaotext.Text = rs(0).Value
nametext.Text = rs(1).Value
sextext.Text = Str(rs(2).Value)
scoretext.Text = Str(rs(3).Value)

End Sub

Private Sub downbtn_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles downbtn.Click
rs.MoveNext()
If rs.EOF = True Then
rs.MoveLast()
End If
xuehaotext.Text = rs(0).Value
nametext.Text = rs(1).Value
sextext.Text = Str(rs(2).Value)
scoretext.Text = Str(rs(3).Value)

End Sub

Private Sub endbtn_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles endbtn.Click
rs.MoveLast()
xuehaotext.Text = rs(0).Value
nametext.Text = rs(1).Value
sextext.Text = Str(rs(2).Value)
scoretext.Text = Str(rs(3).Value)

End Sub

Private Sub 显示学生信息_Load(ByVal sender As Object, ByVal e As

System.EventArgs) Handles MyBase.Load '窗口初始化函数（重点）
Call connect()
rs.MoveFirst()
xuehaotext.Text = rs(0).Value
nametext.Text = rs(1).Value
sextext.Text = Str(rs(2).Value)
scoretext.Text = Str(rs(3).Value)
End Sub
End Class