vb.net最基礎(chǔ)的語(yǔ)句,VB常用語(yǔ)句

VB.NET流程控制語(yǔ)句有哪些

有很多?。∠馡f...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)聽實(shí)例化

reader = mycmd.ExecuteReader()

‘如果執(zhí)行不成功，即沒有得到結(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

reader.Close()

‘關(guān)閉連接

mycon.Close()

End Sub

標(biāo)題名稱：vb.net最基礎(chǔ)的語(yǔ)句,VB常用語(yǔ)句
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