access熟手 容易得的分!! 表达式生成器
SQL SERVER
create table tt1
( id int identity not null,
cha varchar(500),
dd as substring(cha,1,10)+ '... ' --自动获取cha列的前10个字符
)
这个 用access在弄?
在默认值的表达式里写?
还是规则?
怎么写
[解决办法]
access不支持计算列
用查询吧
[解决办法]
Access不支持计算列，SQL Server有公式字段。
Access使用的是Jet-SQL，SQL Server使用的是T-SQL，两者用法上相差很大。
JET SQL 帮助(jet4 access2000)下载地址
http://www.access911.net/index.asp?board=8&recordid=75FAB71E&tt=
[解决办法]
在ACCESS中不能直接做到，用查询才行，ACCESS与SQL SERVER是有区别的。
默认值必须是常量OR内置函数。
[解决办法]
新手来看:设计表的时候怎么定义计算列?《表》
http://access911.net/index.asp?u1=a&u2=74FAB01E13DC
--911--
[解决办法]
wangtiecheng大虾讲的好啊
[解决办法]
但是 有时候 Left 没有定义也 不可以的
考试的时候 就遇到这样的情况
[解决办法]
API函数。
api函数shell_notifyicon
1、新建立一个VB6工程，将Form1的ShowInTaskBar属性设置为False
2、菜单：工程--添加模块 按“打开”这样就添加了一个新模块，名为Module1,保存为Module1.bas
3、在Module1中写下如下代码：
Option Explicit
Public Const MAX_TOOLTIP As Integer = 64
Public Const NIF_ICON = &H2
Public Const NIF_MESSAGE = &H1
Public Const NIF_TIP = &H4
Public Const NIM_ADD = &H0
Public Const NIM_DELETE = &H2
Public Const WM_MOUSEMOVE = &H200
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_LBUTTONUP = &H202
Public Const WM_LBUTTONDBLCLK = &H203
Public Const WM_RBUTTONDOWN = &H204
Public Const WM_RBUTTONUP = &H205
Public Const WM_RBUTTONDBLCLK = &H206
Public Const SW_RESTORE = 9
Public Const SW_HIDE = 0
Public nfIconData As NOTIFYICONDATA
Public Type NOTIFYICONDATA
cbSize As Long
hWnd As Long
uID As Long
uFlags As Long
uCallbackMessage As Long
hIcon As Long
szTip As String * MAX_TOOLTIP
End Type
Public Declare Function ShowWindow Lib "user32 " (ByVal hWnd As Long, ByVal nCmdShow As Long) As Long
Public Declare Function Shell_NotifyIcon Lib "shell32.dll " Alias "Shell_NotifyIconA " (ByVal dwMessage As Long, lpData As NOTIFYICONDATA) As Long
4、在Form1的Load事件中写下如下代码：
Private Sub Form_Load()
'以下把程序放入System Tray====================================System Tray Begin
With nfIconData
.hWnd = Me.hWnd
.uID = Me.Icon
.uFlags = NIF_ICON Or NIF_MESSAGE Or NIF_TIP
.uCallbackMessage = WM_MOUSEMOVE
.hIcon = Me.Icon.Handle
'定义鼠标移动到托盘上时显示的Tip
.szTip = App.Title + "(版本 " & App.Major & ". " & App.Minor & ". " & App.Revision & ") " & vbNullChar
.cbSize = Len(nfIconData)
End With
Call Shell_NotifyIcon(NIM_ADD, nfIconData)
'=============================================================System Tray End
Me.Hide
End Sub
5、在Form1的QueryUnload事件中写入如下代码：
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Call Shell_NotifyIcon(NIM_DELETE, nfIconData)
End Sub
6、在Form1的MouseMove事件中写下如下代码：
Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
Dim lMsg As Single
lMsg = X / Screen.TwipsPerPixelX
Select Case lMsg
Case WM_LBUTTONUP
'MsgBox "请用鼠标右键点击图标! ", vbInformation, "实时播音专家 "
'单击左键，显示窗体
ShowWindow Me.hWnd, SW_RESTORE
'下面两句的目的是把窗口显示在窗口最顶层
'Me.Show
'Me.SetFocus
' ' Case WM_RBUTTONUP
' ' PopupMenu MenuTray '如果是在系统Tray图标上点右键，则弹出菜单MenuTray
' ' Case WM_MOUSEMOVE
' ' Case WM_LBUTTONDOWN
' ' Case WM_LBUTTONDBLCLK
' ' Case WM_RBUTTONDOWN
' ' Case WM_RBUTTONDBLCLK
' ' Case Else
End Select
End Sub
7、现在将程序保存起来运行看看系统托盘处是否增加了一个本工程的图标。单击此图标，Form1就自动弹出来了。
参考资料：http://zhidao.baidu.com/question/1057013.html
[解决办法]
http://support.microsoft.com/kb/162613/zh-cn
http://www.mf100.com/document/2005-8/763.shtml
均有此函数的示例
