vb.net的基础语法

VB.NET编程语法

你这是vb.net的代码,vb中不允许那么写:

Dim

strdx()

As

String

=

{"0",

"0",

"0"}

calcount1

"0"

'定义个字符串变量

strvalue

Boolean

False

'定义strvalue为bool值,改类型变量只有true和false

If

strdx(0)

Then

TextBox1.Text

"."

而

+

ElseIf

True

Else

Select

Case

'

这里开始是分支语句

"+"

Str(Val(strdx(1))

Val(strdx(0)))

高分求.net里vb语法操作数据库基本语句

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

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()

'修改

Dim ids As Integer

ids = 1

Cmd.CommandText = "update main set about='" + TextBox1.Text + "' where id=" + ids.ToString()

'删除

Cmd.CommandText = "delete from main where id=" + ids.ToString()

Public Sub UpdateTable()

Dim Trans As Data.OleDb.OleDbTransaction

Try

Cnn.Open()

Trans = Cnn.BeginTransaction()

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

'error message

'显示

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")

TextBox1.Text = ""

VB.net 中,#if 是什么语法?

#If...Then...#Else 指令

根据条件编译选定的 Visual Basic 代码块,需要有#Const 配对,一般要先用#Const 定义条件编译器常量

'以下是例子

Module Module1

Sub Main()

#End If

End Module

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