Imports System '在程序中包括系统命名空间
Module Module1 VB.Net '完全面向对象,每个程序必须包含一个类的模块,这个类包含程序使用的数据和过程,包含可执行代码,他们定义了类的行为
'This program will display Hello World
Sub Main() '这一行定义了Main过程,它是所有VB.Net程序的入口,Main过程说明了模块或类在执行时将做什么
Console.WriteLine("Hello World") 'WriteLine是System命名空间中定义的Console类的一个方法
Console.ReadKey() '阻止屏幕启动时快速运行和关闭
Imports System
Public Class Rectangle
Private length As Double
Priavate width As Double
'Public methods
Public Sub AcceptDetails()
length = 4.5
width=3.5
End Sub
Public Function GetArea() As Double
GetArea = length * width
End Function
Public Sub Display()
Console.WriteLine("Length:{0}",length)
Console.WriteLine("Width:{0}",width)
Console.WriteLine("Area:{0}",GetArea())
End Sub
Shared Sub Main()
Dim r As New Rectanle()
r.AcceptDetails()
r.Display()
Console.ReadLine()
End Sub
End Class
Module DataTypes
Sub Main()
Dim b As Byte
Dim n As Integer
Dim si As Single
Dim d As Double
Dim da As Date
Dim c As Char
Dim s As String
Dim bl As boolean
b = 1
n = 1234567
si = 0.123456778
d = 0.123456789
da = Today
c = "U"c
s = "Me"
if ScriptEngine = "VB" Then
bl = true
Else
bl = False
End If
If Bl Then
'the oath taking
Console.Write(c & " and," & s & vbCrLf)
Console.WriteLine("declaring on the day of: {0}", da)
Console.WriteLine("We will learn VB.Net seriously")
Console.WriteLine("Lets see what happens to the floating point variables:")
Console.WriteLine("The Single: {0}, The Double: {1}", si, d)
End If
Console.ReadKey()
End Sub
End module
表达式 | 转换成 |
---|---|
CBool | 转换成布尔数据类型 |
CByte | 转成字节数据类型 |
CChar | Char数据类型 |
CDate | Date数据类型 |
CDbl | 双精度数据类型 |
CDec | 十进制数据类型 |
CInT | 整数数据类型 |
CLng | 长数据类型 |
CObj | 对象类型 |
CSByte | SByte数据类型 |
CShort | 短数据类型 |
CSng | 单数据类型 |
CStr | 字符串数据类型 |
CUInt | UInt数据类型 |
CULng | ULng数据类型 |
CUShort | UShort数据类型 |
Module DataTypes
Sub Main()
Dim n As Integer
Dim da As Date
Dim bl As Boolean = True
n = 1234567
da = Today
Console.WriteLine(bl) 'True
Console.WriteLine(CSByte(bl)) '-1
Console.WriteLine(CStr(bl)) 'True
Console.WriteLine(CStr(da)) '21/11/2022
Console.WriteLine(CChar(CChar(CStr(n)))) '1
Console.WriteLine(CChar(CStr(da)))
Console.ReadKey()
End Sub
End Module
constantname 【As datatype】 = initializer
项目 | Value |
---|---|
vbCrLf | 回车/换行字符组合 |
vbCr | 回车字符 |
vbLf | 换行字符 |
vbNewLine | 换行字符 |
vbNullChar | 空字符 |
vbNullString | 不等于零长度字符串(“”),用于调用外部过程 |
vbObjectError | $1 |
vbTab | 标签字符 |
vbBack | 退格字符 |
Module constantsEnum
Enum Colors
red = 1
orange = 2
yellow = 3
green = 4
azure = 5
blue = 6
violet = 7
End Enum
Sub Main()
Console.WriteLine("The Color Red is : " & Colors.red)
Console.WriteLine("The Color Orange is : " & Colors.orange)
Console.ReadKey()
End Sub
End Module
创建OraDynaset对象执行SQL命令,我们可以使用DbCreateDynaset来创建记录集。
编辑数据记录:我们使用OraDynaset方法实现对数据记录的编辑;
'通过OO4O连接数据库,通过执行Select语句选择数据
Private Sub DBSelect()
On Error GoTo Err_Rtn
Dim OraSession As OraSession
Dim OraDatabase As OraDatabase
Dim OraDynaset As OraDynaset
Dim result
Dim strSQL strSQL = "SELECT * FROM HINMST WHERE MAKERCODE = '123'" 'SQL
Set OraSession = CreateObject("OracleInProcServer.XOraSession") 'oo4oObject
Set OraDatabase = OraSession.OpenDatabase("hogesvr", "hogeu/hogep", ORADB_DEFAULT)'连接DB
Set OraDynaset = OraDatabase.CreateDynaset(strSQL, ORADYN_READONLY) '执行SQL
MsgBox OraDynaset.RecordCount & "件数据被抽出"
While Not OraDynaset.EOF '循环所有的数据
MsgBox OraDynaset.Fields("NAME").Value '取得相应的列值
OraDynaset.MoveNext '下一次循环
DoEvents Wend Set OraDynaset = Nothing '释放资源
Set OraDatabase = Nothing '释放资源
Set OraSession = Nothing '释放资源
Exit Sub '==============' 错误处理'==============
Err_Rtn: If (OraSession.LastServerErr <> 0) Then 'OraSession Error MsgBox
OraSession.LastServerErrText '表示Error内容
OraSession.LastServerErrReset '清空Error
Set OraSession = Nothing '释放资源
ElseIf (OraDatabase.LastServerErr <> 0) Then 'OraDatabase Error
MsgBox OraDatabase.LastServerErrText '表示Error内容
OraDatabase.LastServerErrReset '清空Error
Set OraDatabase = Nothing '释放资源
Set OraSession = Nothing '释放资源
Else
MsgBox Err.Description '表示Error内容
Set OraDynaset = Nothing '释放资源
Set OraDatabase = Nothing '释放资源
Set OraSession = Nothing '释放资源
End If
End Sub
Oracle objects for OLE(OO4O)是一组软件层,其设计目的是使微软COM自动化和ActiveX兼容的语言直接访问Oracle数据库,
注意:在单元格中先写 “=” 号,视为公式