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VB.NET流程控制語(yǔ)句有哪些
有很多啊！像If...else..,For...Next,Do...Loop等
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要詳細(xì)的看MSDN吧：
高分求.net里vb語(yǔ)法操作數(shù)據(jù)庫(kù)基本語(yǔ)句
Dim Cnn As New Data.OleDb.OleDbConnection
Dim DbAdapter As New Data.OleDb.OleDbDataAdapter
Dim Cmd As New Data.OleDb.OleDbCommand
Dim dsAll As New Data.DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Cnn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\webapp\test\web.mdb"
Cmd.Connection = Cnn
End Sub
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
'插入
Cmd.CommandText = "insert into main (about) values ('" + TextBox1.Text + "')"
UpdateTable()
End Sub
Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
'修改
Dim ids As Integer
ids = 1
Cmd.CommandText = "update main set about='" + TextBox1.Text + "' where id=" + ids.ToString()
UpdateTable()
End Sub
Protected Sub Button3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button3.Click
'刪除
Dim ids As Integer
ids = 1
Cmd.CommandText = "delete from main where id=" + ids.ToString()
UpdateTable()
End Sub
Public Sub UpdateTable()
Dim Trans As Data.OleDb.OleDbTransaction
Try
Cnn.Open()
Trans = Cnn.BeginTransaction()
Try
Cmd.Transaction = Trans
Cmd.ExecuteNonQuery()
Trans.Commit()
Catch
Trans.Rollback()
Finally
If (Cnn.State = System.Data.ConnectionState.Open) Then
Cnn.Close()
End If
End Try
Catch
'error message
End Try
End Sub
Protected Sub Button4_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button4.Click
'顯示
Cmd.CommandText = "select id, about from main"
DbAdapter.SelectCommand = Cmd
DbAdapter.Fill(dsAll, "table1")
If (dsAll.Tables("table1").Rows.Count 0) Then
TextBox1.Text = dsAll.Tables("table1").Rows(0)("about")
Else
TextBox1.Text = ""
End If
End Sub
VB.NET的 把重點(diǎn)的語(yǔ)句注釋下就行了
'''兩段程序就是利用.net的連接對(duì)象的功能來(lái)完成登錄的實(shí)例
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click 'start按鈕觸發(fā)的函數(shù)
Dim schclass As String = Trim(txtClass.Text) ‘將txtClass里文本賦值給變量schclass
Dim selestr As String
’提示用戶txtClass文本框不能為空
If schclass "" Then
selestr = "班級(jí)='" schclass "'"
Else
MsgBox("請(qǐng)輸入班級(jí)名稱", 64, "提示") ‘ 顯示保存成功提示信息
End If
‘創(chuàng)建一個(gè)DataView對(duì)象，即將數(shù)據(jù)集DataSet11里的學(xué)生成績(jī)表的DefaultView實(shí)例化
Dim dvresult As DataView = DataSet11.學(xué)生成績(jī).DefaultView
’按學(xué)號(hào)字段排序
dvresult.Sort = "學(xué)號(hào)"
‘按剛才txtClass里輸入的班級(jí)查詢
dvresult.RowFilter = selestr
dvresult.RowStateFilter = DataViewRowState.CurrentRows
’然后將篩選的結(jié)果輸入到datagrid上
DataGrid1.DataSource = dvresult
End Sub
Private Sub btnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOK.Click ‘ok按鈕觸發(fā)的函數(shù)
’如果txtUserName或txtPass文本框?yàn)榭?，提示并中斷函?shù)
If txtUserName.Text = "" Or txtPass.Text = "" Then
Response.Write("script language=vbscriptalert""用戶名或密碼不能為空！""/script")
Exit Sub
End If
‘定義鏈接、執(zhí)行、閱讀 對(duì)象
Dim mycon As New OleDbConnection
Dim mycmd As New OleDbCommand
Dim reader As OleDbDataReader
’給連接對(duì)象賦值連接字符串，access類型的。
mycon.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" _
Server.MapPath("Msg.mdb")
‘打開(kāi)連接對(duì)象
mycon.Open()
’將連接對(duì)象復(fù)制到執(zhí)行對(duì)象上
mycmd.Connection = mycon
‘然后就給執(zhí)行對(duì)象賦值執(zhí)行類型和執(zhí)行語(yǔ)句
mycmd.CommandType = CommandType.Text
mycmd.CommandText = "Select * from myuser Where 用戶名='" txtUserName.Text "'" " and 密碼='" txtPass.Text "'"
’然后將執(zhí)行對(duì)象的監(jiān)聽(tīng)實(shí)例化
reader = mycmd.ExecuteReader()
‘如果執(zhí)行不成功，即沒(méi)有得到結(jié)果集就提示否則將結(jié)果集的用戶名賦值給一個(gè)session以供其他頁(yè)面使用
If reader.Read = False Then
Response.Write("script language=vbscriptalert""用戶名或密碼錯(cuò)，你不能登錄！""/script")
Else
Session("username") = reader("用戶名")
Response.Redirect("lwmsg.aspx")
End If
’關(guān)閉監(jiān)聽(tīng)
reader.Close()
‘關(guān)閉連接
mycon.Close()
End Sub
當(dāng)前名稱：vb.net最基礎(chǔ)的語(yǔ)句,VB常用語(yǔ)句
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