1.创建索引
create index PENALTIES_AMOUNT on penalties(amount);
删除： drop index PENALTIES_AMOUNT;
2.创建索引
create view number_sets (matchno,difference) as select matchno,abs(won-lost) from matches;
删除： drop view number_sets;
使用方法:
select * from number_sets;
3.对用户限制在某个表操作
grant select ,update on players to dinnery
posted @ 2011-05-30 17:23 alon 阅读(28) 评论(0) 编辑
第一章。现代JS程序设计
分离式DOM脚本编程
使用DOM定位并操作不同的DOM元素
<html>
<head>
<title> introduction to the dom </title>
<script>
//我们必须在文档完成加载后再操作DOM
window.onload = function() {
//获取文档中的所有 <li>
var li = document.getElementsByTagName("li");
//并给它们全部添加一个黑边框
for(var j=0;j<li.length;j++)
{
li[j].style.border = "1px solid #000";
}
//添加事件处理函数
for(var i=0;i< li.length;i++)
{
li[i].onmouseover = function()
{
this.style.backgroundColor = 'blue';
};
li[i].onmouseout = function(){
this.style.backgroundColor = 'white'; //大小写必须全对，否则不显示。
};
}
//获取ID 为 'everywhere'的元素，并从文档中删除
var every = document.getElementById("everywhere");
every.parentNode.removeChild(every);
};
</script>
</head>
<body>
<h1> introduction to the dom</h1>
<ul>
<li id="everywhere">it can be found.</li>
<li class="test"> it's easy to use.</li>
</ul>
</body>
</html>
第二章 面向对象的JS
引用
1.多个变量引用同一个对象
//将OBJ 设置为空对象
var obj = new Object();
// objRef 现在是另一个对象的引用
var objRef = obj;
//修改原对象的一个属性
obj.oneProperty = true;
//我们现在看到，这个改变在两个变量中都反映出来了，因为他们引用的是同一对象）
alert(obj.oneProperty == objRef.oneProperty);
2. 自修改对象的例子
//创建一个数组
var items = new Array("one","two");
//创建数组的一个引用
var itemsRef = items;
//将一个元素添加到原数组中
items.push("six");
//这两数组长度一样，因为他们指向同一个数组对象
3.修改对象的引用，同时保持完整性
//将items 设置为字符串的数组
var items = new Array("one","two");
//将itemsRef 设置为items的引用
var itemsRef = items;
//将items 设置为一个新对象
items = new Array("new","array");
//items 和itemsRef 现在指向不同的对象了。
alert(items != itemsRef);
4.修改对象而生成新对象
//将item设置为一个新的字符串对象
var item = "test";
//itemRef 现在指向同一个字符串对象
var itemRef = item;
//将一些新文本接在这字符串后面， 注意，这会创建一个新的对象，而非修改原对象
item += "ing";
//item 和 itemRef值不相等了，因为新的字符串对象已被创建
alert(item != itemRef);
判断对象类型
1. typeof
if(typeof num == "string )
num = parseInt(num);
2. 使用构造函数属性来判断对象的类型
//检测我们的数学实际上是否为字符串
if(nu.constructor == String)
num = parseInt(num);
//是否为数组
if(str.constructor == Array)
str = str.join(',');
变量的类型检测
变量 typeof变量 变量。构造函数
{an:"object"} object Object
["an","array"] object Array
function(){} function Function
"a string" string String
55 number Number
true boolean Boolean
new User() object User
一个函数，可以用来严格维护传入函数的所有参数
//用一个变量类型列表严格检查一个参数列表
function strict(types, args)
{
//保证类型的数量和参数的数量相匹配
if(types.length != args.length)
{
//否则抛出一个有用的异常
throw "Invalid number of arguments .Expected " + types.length + ", received " + args.length + " instead.";
}
//遍历所有的参数，检查它们的类型
for(var i=0 ; i < args.length ; i++)
{
if(args[i].constructor != types[i])
{
throw "Invalid argument type. Expected " + types[i].name + ",received " + args[i].constructor.name + " instead.";
}
}
}
//一个简单的函数，打印用户列表
function userList(prefix, num,users)
{
//保证prefix 是字符串， num 是数字 , users 是数组
strict( [String,Number,Array], arguments);
//遍历 'num' 个用户
for(var i=0; i <num ;i++)
{
//显示每个用户的信息
print( prefix + ":" + users[i]);
}
}
闭包:(closure)
1.闭包如何使代码更清晰
//找出ID为‘main'的元素
var obj = document.getElementById("main");
//修改样式
obj.style.border = "1px solid red";
//初始化一个在一秒后执行的回调函数( callback)
setTimeout(function() {
//它将隐藏此对象
obj.style.display = 'none';
},1000);
//一个用于延时显示警告信息的通用函数
function delayedAlert(msg,time) {
//初始化一个封装的回调函数
setTimeout(function() {
// 它将使用包含本函数的外围函数传入的 msg变量
alert(msg);
},time};
}
//用两个参数调用 delayedAlert函数
delayedAlert("welcome!",2000);
posted @ 2010-02-04 10:19 alon 阅读(39) 评论(0) 编辑
Rundll32包含了很多系统的指令，下面是我摘录的关于Rundll32可以执行的命令集合。
To bring up the "Format - 3 1/2 Floppy (A:)" window:
rundll32.exe shell32.dll,SHFormatDrive
To bring up the Control Panel "Date/Time Properties" window:
rundll32.exe shell32.dll,Control_RunDLL timedate.cpl
To bring up the Control Panel "Display Properties" window:
rundll32.exe shell32.dll,Control_RunDLL desk.cpl
To bring up the Control Panel "Display Properties" window and open the third tab (the third tab is 2 because the first tab is 0):
rundll32.exe shell32.dll,Control_RunDLL timedate.cpl,@0,2
To bring up the Control Panel "Network" window:
rundll32.exe shell32.dll,Control_RunDLL netcpl.cpl
To bring up the Control Panel "System Properties" window:
rundll32.exe shell32.dll,Control_RunDLL sysdm.cpl
To shut windows down using the Windows 3.1 API:
rundll user,exitwindows
or you can use the number that Quick View displays alongside the function name:
rundll user,#7
To try for a reboot using the Windows 3.1 API:
rundll user,exitwindowsexec
or
rundll user,#246
To shut Windows down using the Win32 API
rundll32 user.exe,#7
Make a beep
rundll user,messagebeep
rundll32 user.exe,messagebeep
rundll32 user.exe,#104
Shuts off COM2 serial port if the port was opened under the Windows 3.1 API
rundll user,closecomm
rundll32 user.exe,closecomm
rundll32 user.exe,#207
Polite windows restart
rundll user,exitwindowsexec
Polite power off
rundll user,exitwindows
rundll32 user.exe,exitwindows
rundll32 user.exe,#7
Forced immediate logoff
rundll32 user32.dll,ExitWindowsEx
Open DUN (dial up networking exported file):
rundll32.exe rnaui.dll,RnaRunImport
Start a dialup connection by name
rundll32.exe rnaui.dll,RnaDial %1
NetMeeting Speeddial CNF:
rundll32.exe msconf.dll,OpenConfLink %l
H.323 -or- Intel IPhone Internet telephony:
rundll32.exe msconf.dll,NewMediaPhone %l
URL Callto:
rundll32.exe msconf.dll,CallToProtocolHandler %l
URL:
rundll32.exe shdocvw.dll,OpenURL %l
URL Rlogin / Telnet / TN3270:
rundll32.exe url.dll,TelnetProtocolHandler %l
Email rfc822 EML:
rundll32.exe c:\windows\SYSTEM\mailnews.dll,EMLFileHandler
News rfc822 NWS:
rundll32.exe c:\windows\SYSTEM\mailnews.dll,News_RunDLL
URL File:
rundll32.exe url.dll,FileProtocolHandler %l
URL Mailto:
rundll32.exe c:\windows\SYSTEM\mailnews.dll,Mail_RunDLL
INF install:
C:\WINDOWS\rundll.exe setupx.dll,InstallHinfSection DefaultInstall 132
INF active install
rundll32.exe advpack.dll,LaunchINFSection %1, DefaultInstall
New briefcase
C:\WINDOWS\rundll32.exe syncui.dll,Briefcase_Create %1!d! %2
New LNK
RunDLL32 AppWiz.Cpl,NewLinkHere %1
open aif
rundll32 amovie.ocx,RunDll %1
play aif
rundll32 amovie.ocx,RunDll /play /close %1
open auf
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /open %1
play auf
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /play /close %1
open avi
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /open %1
play avi
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /play /close %1
open channel file
rundll32 cdfview.dll,OpenChannel %L
subscribe to channel
rundll32 cdfview.dll,Subscribe %L
print HTML
rundll32.exe C:\WINDOWS\SYSTEM\MSHTML.DLL,PrintHTML "%1"
printto HTML
rundll32.exe C:\WINDOWS\SYSTEM\MSHTML.DLL,PrintHTML "%1" "%2" "%3" "%4"
open midi
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /open %1
play midi
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /play /close %1
open MOV
rundll32 amovie.ocx,RunDll %1
play MOV
rundll32 amovie.ocx,RunDll /play /close %1
open MPEG
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /open %1
play MPEG
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /play /close %1
open sound
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /open %1
play sound
C:\WINDOWS\rundll32.exe C:\WINDOWS\SYSTEM\amovie.ocx,RunDll /play /close %1
open unknown file
C:\WINDOWS\rundll32.exe shell32.dll,OpenAs_RunDLL %1
install screensaver
C:\WINDOWS\rundll32.exe desk.cpl,InstallScreenSaver %l
More great RUNDLL tips:
http://www.mvps.org/vb/tips/shellcpl.txt
posted @ 2010-01-26 21:18 alon 阅读(151) 评论(0) 编辑
posted @ 2010-01-26 21:17 alon 阅读(35) 评论(0) 编辑
VC常用数据类型(2006.11.26):
类型 字节数 位数 范围 备注意:
char 1 8 -128-127
signed char 1 8 -128-127
unsigned char 1 8 0-255
short int 2 16 -32768-32767
signed short int 2 16 -32768-32767
unsigned short int 2 16 0-65535
int 4 32 -2147483648-2147483647
signed int 4 32 -2147483648-2147483647
unsigned int 4 32 0-4294967259
long int 4 32 -2147483648-2147483647
signed long int 4 32 -2147483648-2147483647
unsigned long int 4 32 0-4294967259
long 4 32 -2,147,483,648 to 2,147,483,647
float 4 32 3.4E +/- 38 (7 digits)
double 8 64 1.7E +/- 308 (15 digits)
long double 10 80 1.2E +/- 4932 (19 digits)
以下为windef.h中有关VC常用数据类型的定义:
typedef unsigned long DWORD;
typedef int BOOL;
typedef unsigned char BYTE;
typedef unsigned short WORD;
typedef float FLOAT;
typedef FLOAT *PFLOAT;
typedef BOOL near *PBOOL;
typedef BOOL far *LPBOOL;
typedef BYTE near *PBYTE;
typedef BYTE far *LPBYTE;
typedef int near *PINT;
typedef int far *LPINT;
typedef WORD near *PWORD;
typedef WORD far *LPWORD;
typedef long far *LPLONG;
typedef DWORD near *PDWORD;
typedef DWORD far *LPDWORD;
typedef void far *LPVOID;
typedef CONST void far *LPCVOID;
typedef int INT;
typedef unsigned int UINT;
typedef unsigned int *PUINT;
typedef WORD ATOM;
1.使用sizeof( )可以得到任何对象占用的字节数，例如如果有一个char类型的变量a， 则sizeof(a)会返1.
2.还可以借助typedef定义自己的数据类型，例如typedef myint unsigned int;后myint就等价于unsigned int.
posted @ 2010-01-26 21:14 alon 阅读(55) 评论(0) 编辑
1.集合的用法
(1)
IN 判断是否存在
type
TCharset = set of char;
var
t: TCharset;
begin
t:= ['a','b','s'];
if 's' in t then
ShowMessage('in');
end;
判断是否缺乏
if not ('m' in t) then
// do something
(2)增加删除
+ ,-
Include(t,'m');
ExClude(t,'a');
(3)交集
if ['a','b']*t=['a','b'];
2.什么时候用new
new()给指向已知大小的结构的指针分配内参，记住用Dispose()释放new()申请的任何内存
用GetMem()或AllowMem()给未知大小的结构分配内存。并用FreeMem()清除
AllowMem()比GetMem()安全，因为把申请到的内存初始为零
3. 创建命名类型完成a对b的赋值
type
PtrInteger = ^Integer;
var
a,b:PtrInteger;
4.类型别名
type
MInt :Integer;
强类型(strongly typed):
type
MInt = type integer; (MInt 与Integer不兼容)
5.类型转换
只有两个变量的数据占用的内存大小相同时才能进行
浮点转整数:Trimc()或者Round()
整数到浮点: 使用赋值
6.字符串资源:
resourcestring:
resstring ='resource'
7.参数传递
--------------------------------------
1.值参数
procedure fun(s:string);
2.引用参数
procedure fun(var s:string);
3.常量参数
procedure fun(const s:string);
4.开放数组
function fun(a:array of integer):integer;
使用high(),low(),sizeof()获得数组信息
----------------------------------------
8.
posted @ 2010-01-26 21:12 alon 阅读(21) 评论(0) 编辑
-.
1.数据类型存储
*1.堆栈:存储固定长度的数据,如int(占4字节). 值类型
*2.堆:存储可变长度的数据,如字符串. 引用类型
结构是值类型，类是引用类型
2.多维数组
string[,] Name={{"Lennon","John"},{"MAC","Paul"}};
3.
internal 变量只能在当前程序中被访问
protected internal 变量只能在当前程序中被访问，或者在派生当前类型的其他类型中被访问
4. Static
必须通过类直接访问该变量，而不能通过实例访问
5.Checked 与Unchecked
执行溢出检查
byte b= 255;
checked{
b++;
}
6. is 检查对象是否与特定的类型兼容.
int i =10;
if(i is object)
{
}
7.类方法
virtual 方法可以被其派生的类重写
New 方法隐藏了同名的继承方法
Abstract 这个虚拟方法定义了方法名，但没有提供执行方式.不能实例化，只能派生.
override 方法重写继承的方法或抽象的方法
Sealed 方法重写继承的虚拟方法，但不能被派生于这个类的其他类重写，必须和重写方法一起使用。
8.方法输入参数
*1.
using System;
class ParentClass
{
static void SomeFunction(int[] ints,int i)
{
ints[0]=1000;
i=0;
}
public static void Main()
{
int i = 200;
int[] ints={1,2,3,4};
SomeFunction(ints,i);
Console.WriteLine("i="+i);
Console.WriteLine("ints[0]="+ints[0]);
}
}
结果 200 ,1000 数组的值将改变.
*2.
using System;
class ParentClass
{
static void SomeFunction(int[] ints,ref int i)
{
ints[0]=1000;
i=0;
}
public static void Main()
{
int i = 200;
int[] ints={1,2,3,4};
SomeFunction(ints,ref i);
Console.WriteLine("i="+i);
Console.WriteLine("ints[0]="+ints[0]);
}
}
结果 0,1000 两方面值都将改变。 Ref用法
9. Out用法
using System;
class ParentClass
{
static void SomeFunction(out int i)
{
i= 200;
}
public static void Main()
{
int i ;
SomeFunction(out i);
Console.WriteLine(i);
}
}
----------------------------------
二: 类
1.实例和静态方法
如果方法不试图访问实例数据或其他实例方法，可以声明为static.不能在声明为static的方法中访问实例字段.
public class TestClass
{
private static unit minpasswordlength = 6;
public static uint getminpasswordlength()
{
return mimpasswordlength;
}
2.命名空间别名
using alias = NameSpaceName;
3.属性
*1.private static uint MinPasswordLength
{
get
{
return minPasswordLength;
}
set
{
if(value<=10)
minPasswordLength = value;
else
Console.WriteLine("Error");
}
}
*2.
public bool ChangePassword(string oldPassword,string newPassword)
{
if(oldPassword==Password&&newPassword.Length>=minPasswordLength)
{
Password =newPassword;
return true;
}
else
{
return false;
}
}
*3.
public decimal SubTotal{
get{return _price*_quantity;}
}
4.Const
值不能改变，并且必须在定义的时候设置。
public const uint MaxPasswordLength = 6;
隐式静态，对它必须用静态成员的语法，也就是类名.
Authenticator Julian = new Authenticator();
uint Max1 = Authenticator.maxPasswordLength;
uint Max2 = Julian.maxPasswordLength;
posted @ 2010-01-26 21:11 alon 阅读(35) 评论(0) 编辑
1.
句柄(HANDLE)的东西。可以这样去理解句柄，Windows程序中产生的任何资源（要占用某一块或大或小的内存），如图标，光标，窗口，应用程序的实例（已加载到内存运行中的程序）。操作系统每产生一个这样的资源时，都要将它们放入相应的内存，并为这些内存指定一个唯一的标识号，这个标识号即该资源的句柄。
2.创建光标
CClientDC dc(this);
CFont font;
font.CreatePointFont(200,"宋体");
dc.SetTextColor(RGB(0,0,255));
dc.SelectObject(&font);
TEXTMETRIC tm;
dc.GetTextMetrics(&tm);
CreateSolidCaret(tm.tmAveCharWidth/8,tm.tmHeight);
ShowCaret();
VC++深入详解 2007.1.16
第一章: windows程序内部运行机制
1. HWND 类型标识窗口。HINSTANCE 实例句柄.
2. typeded struct _WNDCLASS {}
位或操作: style = CS_HREDRAW|CS_VREDRAW;
取反~:
与&:
去掉先前style 的CS_VREDRAW: style=style&~CS_VREDRAW;
3:回调函数: 不是由该函数的实现方直接调用，而是在特定的事件或条件发生时由另外一方调用，用于对该事件或条件进行响应。
实现机制:
*1: 定义一个回调函数.
*2: 提供函数实现的一方在初始化的时候，将回调函数的函数指针注册给调用者。
*3: 当特定的事件或条件发生的时候，调用者使用函数指针调用回调函数对事件进行处理。
WNDPROC的定义(它被定义为指向窗口过程函数指针类型，格式必须与WNDPROC相同。
typedef LRESULT (CALLBACK* WNDPROC)(HWND,UINT,WPARAM,LPARAM);
WINDOWS程序中，回调函数必须遵循_stdcall 调用约定， 所以要使用CALLBACK.
4.HICON LoadIcon(HINSTANCE ,LPCTSTR)
LPCTSTR: CONST CHAR * 指向字符常量的指针。 用MAKEINTRESOURCE转换图标ID(整数).
5. GetMessage 除WM_QUIT外返回非0,WM_QUIT返回0,出现错误返回-1.
MSG msg;
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg); //虚拟键消息转为字符消息,投递到调用线程的消息队列。
DispatchMessage(&msg);
}
非0即为真
MSDN:
BOOL bRet;
while((bRet = GetMessage(&msg,NULL,0,0))!=0)
{
if(bRet==-1)
{
}
else
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
第二章 C++
1. 结构体默认情况下，其成员是公有(Public)的，类默认情况下，其成员是私有的。
2.多态: 在基类的函数前加上virtual关键字，在派生类中重写该函数，运行时将会根据对象的实际类型来调用相应的函数。
c++的多态性是由虚函数来实现的，而不是纯虚函数，在子类中如果有对基类虚函数的覆盖定义，无论该覆盖定义是否有virtual关键字，都是虚函数。
3.纯虚函数:
virtual void fun()=0
在派生类中必须完全实现基类的纯虚函数。
第四章:
1.SDK画线
HDC dc;
dc = ::GetDC(m_hWnd);
MoveToEx(dc,m_pt.x,m_pt.y,NULL);
LineTo(dc,point.x,point.y);
::ReleaseDC(m_hWnd,hdc);
MFC 画线
CDC* pdc = GetDC();
pdc->MoveTo(m_pt.x,m_pt.y);
pdc->LineTo(point.x,point.y);
ReleaseDC(pdc);
CClientDC 类画线 //可画到工具栏
CClientDC dc(GetParent());
dc.MoveTo(m_pt.x,m_pt.y);
dc.LineTo(point.x,point.y);
CWindowDC 类画线 //可画到工具栏，菜单栏
CWindowDC dc(GetParent());
dc.MoveTo(m_pt.x,m_pt.y);
dc.LineTo(point.x,point.y);
//在桌面上画线
CWindowDC dc(GetDesktopWindow());
dc.MoveTo(m_pt.x,m_pt.y);
dc.LineTo(point.x,point.y);
2.彩色线条
CPen pen(PS_SOLID,1,RGB(255,0,255));
CClientDC dc(this);
CPen *pens = dc.SelectObject(&pen);
dc.MoveTo(m_pt.x,m_pt.y);
dc.LineTo(point.x,point.y);
dc.SelectObject(pens);
PS_DASH:画笔的宽度小于等于1时，才有效。
3.
简单笔刷
CBrush brush(RGB(255,0,255));
CClientDC dc(this);
dc.FillRect(CRect(m_pt,point),&brush);
位图刷
CBitmap bmp;
bmp.LoadBitmap(IDR_FFFTYPE);
CBrush brush(&bmp);
CClientDC dc(this);
dc.FillRect(CRect(m_pt,point),&brush);
透明刷
CClientDC dc(this);
CBrush *pBrush = CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));
CBrush *pOldBrush = dc.SelectObject(pBrush);
dc.Rectangle(CRect(m_pt,point));
dc.SelectObject(pOldBrush);
画刷句柄转换成画刷对象 FromHandle
4.静态成员函数和静态成员变量属于类本身，在类加载的时候，即为它们分配了空间，所以可以通过类名::函数名 或类名:变量名来访问，而非静态成员函数和非静态成员属于对象的方法和数据，也就是应该首先产生类的对象，然后通过类的对象去引用。
在静态成员函数中是不能调用非静态成员的，包括非静态成员函数和非静态成员变量。
第五章:
1.文本插入符
CClientDC dc(this);
TEXTMETRIC tm;
dc.GetTextMetrics(&tm);
CreateSolidCaret(tm.tmAveCharWidth/8,tm.tmHeight);
ShowCaret();
BMP插入符
CBitmap bmp;
bmp.LoadBitmap(IDB_BITMAP1);
CreateCaret(&bmp);
ShowCaret();
2.路径P159
对GetTextMetrics函数来说,它获得的是设备描述表中当前字体的度量信息,而GetTextExtent函数则是
获得某个特定的字符串在窗口中显示时所占据的宽度和高度。
第六章:
1.响应菜单项命令的顺序依次是:视类,文档类，框架类，应用程序类。
posted @ 2010-01-26 21:10 alon 阅读(36) 评论(0) 编辑
第4章 基本控制流
零警告编译
int pennies = static_cast<int>(100 * (amount_due - amount_paid));
输入确定
#include<iostream>
#include<string>
#include<cmath>
using namespace std;
int main()
{
double area;
cout<< "Please enter the area of a square:";
cin>>area;
if(cin.fail())
{
cout<<"error:bad input\n";
return 1;
}
if( area < 0)
{
cout<<"error : negaive area\n";
return 1;
}
}
函数注释风格
/**
计算
@param x
@param y
@return
**/
#include<iostream>
#include<string>
#include<cmath>
using namespace std;
/**
测试两个浮点数是否相近
@param x
@param y
@return true 若近识相等则为真
**/
bool approx_equal(double x,double y)
{
const double EPSION = 1E-14;
if(x==0) return fabs(y) <= EPSION;
if(y==0) return fabs(x) <= EPSION;
return fabs(x-y) / max(fabs(x),fabs(y)) <= EPSION;
}
int main()
{
double x;
cout<<"Enter a number;";
cin >>x;
double y;
cout<<"Enter another number;";
cin>>y;
if(approx_equal(x,y))
cout<<"the numbers are approximately equal.\n";
else
cout<<" the numbers are different.\n";
return 0;
}
第九章
1. C++中 实现数据项序列有更好的办法： 向量结构。
2.vector<double> salaries;
salaries[0] = 32000;
若定义向量时不带长度参数，它将是空的并不能保持元素。
3.
posted @ 2010-01-23 00:54 alon 阅读(73) 评论(0) 编辑
15个mysql使用管理命令
In all the 15 mysqladmin command-line examples below, tmppassword is used as the MySQL root user password. Please change this to your MySQL root password.
1. How to change the MySQL root user password?
# mysqladmin -u root -ptmppassword password 'newpassword'
# mysql -u root -pnewpassword
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.1.25-rc-community MySQL Community Server (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql>
2. How to check whether MySQL Server is up and running?
# mysqladmin -u root -p ping
Enter password:
mysqld is alive3. How do I find out what version of MySQL I am running?
Apart from giving the ‘Server version’, this command also displays the current status of the mysql server.
# mysqladmin -u root -ptmppassword version
mysqladmin Ver 8.42 Distrib 5.1.25-rc, for redhat-linux-gnu on i686
Copyright (C) 2000-2006 MySQL AB
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license
Server version 5.1.25-rc-community
Protocol version 10
Connection Localhost via UNIX socket
UNIX socket /var/lib/mysql/mysql.sock
Uptime: 107 days 6 hours 11 min 44 sec
Threads: 1 Questions: 231976 Slow queries: 0 Opens: 17067
Flush tables: 1 Open tables: 64 Queries per second avg: 0.254. What is the current status of MySQL server?
# mysqladmin -u root -ptmppassword status
Uptime: 9267148
Threads: 1 Questions: 231977 Slow queries: 0 Opens: 17067
Flush tables: 1 Open tables: 64 Queries per second avg: 0.25The status command displays the following information:
Uptime: Uptime of the mysql server in seconds
Threads: Total number of clients connected to the server.
Questions: Total number of queries the server has executed since the startup.
Slow queries: Total number of queries whose execution time waas more than long_query_time variable’s value.
Opens: Total number of tables opened by the server.
Flush tables: How many times the tables were flushed.
Open tables: Total number of open tables in the database.
5. How to view all the MySQL Server status variable and it’s current value?
# mysqladmin -u root -ptmppassword extended-status
+-----------------------------------+-----------+
| Variable_name | Value |
+-----------------------------------+-----------+
| Aborted_clients | 579 |
| Aborted_connects | 8 |
| Binlog_cache_disk_use | 0 |
| Binlog_cache_use | 0 |
| Bytes_received | 41387238 |
| Bytes_sent | 308401407 |
| Com_admin_commands | 3524 |
| Com_assign_to_keycache | 0 |
| Com_alter_db | 0 |
| Com_alter_db_upgrade | 0 |6. How to display all MySQL server system variables and the values?
# mysqladmin -u root -ptmppassword variables
+---------------------------------+---------------------------------+
| Variable_name | Value |
+---------------------------------+---------------------------------+
| auto_increment_increment | 1 |
| basedir | / |
| big_tables | OFF |
| binlog_format | MIXED |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | latin1 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
skip.....
| time_format | %H:%i:%s |
| time_zone | SYSTEM |
| timed_mutexes | OFF |
| tmpdir | /tmp |
| tx_isolation | REPEATABLE-READ |
| unique_checks | ON |
| updatable_views_with_limit | YES |
| version | 5.1.25-rc-community |
| version_comment | MySQL Community Server (GPL) |
| version_compile_machine | i686 |
| version_compile_os | redhat-linux-gnu |
| wait_timeout | 28800 |
+---------------------------------+---------------------------------+7. How to display all the running process/queries in the mysql database?
# mysqladmin -u root -ptmppassword processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+----+---------+------+-------+------------------+
| 20 | root | localhost | | Sleep | 36 | | |
| 23 | root | localhost | | Query | 0 | | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+You can use this command effectively to debug any performance issue and identify the query that is causing problems, by running the command automatically every 1 second as shown below.
# mysqladmin -u root -ptmppassword -i 1 processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+----+---------+------+-------+------------------+
| 20 | root | localhost | | Sleep | 36 | | |
| 23 | root | localhost | | Query | 0 | | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+----+---------+------+-------+------------------+
| 24 | root | localhost | | Query | 0 | | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+8. How to create a MySQL Database?
# mysqladmin -u root -ptmppassword create testdb
# mysql -u root -ptmppassword
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 705
Server version: 5.1.25-rc-community MySQL Community Server (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| sugarcrm |
| testdb |
+--------------------+
4 rows in set (0.00 sec)
Note: To display all tables in a database, total number of columns, row, column types, indexes etc., use the mysqlshow command that we discussed in our previous articles.
9. How to Delete/Drop an existing MySQL database?
# mysqladmin -u root -ptmppassword drop testdb
Dropping the database is potentially a very bad thing to do.
Any data stored in the database will be destroyed.
Do you really want to drop the 'testdb' database [y/N] y
Database “testdb” dropped
# mysql -u root -ptmppassword
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 707
Server version: 5.1.25-rc-community MySQL Community Server (GPL)
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.
mysql> show databases;
+——————–+
| Database |
+——————–+
| information_schema |
| mysql |
| sugarcrm |
+——————–+
3 rows in set (0.00 sec)10. How to reload/refresh the privilege or the grants tables?
# mysqladmin -u root -ptmppassword reload;Refresh command will flush all the tables and close/open log files.
# mysqladmin -u root -ptmppassword refresh11. What is the safe method to shutdown the MySQL server?
# mysqladmin -u root -ptmppassword shutdown
# mysql -u root -ptmppassword
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/lib/mysql/mysql.sock'Note: You can also use “/etc/rc.d/init.d/mysqld stop” to shutdown the server. To start the server, execute “/etc/rc.d/init.d/mysql start”
12. List of all mysqladmin flush commands.
# mysqladmin -u root -ptmppassword flush-hosts
# mysqladmin -u root -ptmppassword flush-logs
# mysqladmin -u root -ptmppassword flush-privileges
# mysqladmin -u root -ptmppassword flush-status
# mysqladmin -u root -ptmppassword flush-tables
# mysqladmin -u root -ptmppassword flush-threadsflush-hosts: Flush all information in the host cache.
flush-privileges: Reload the grant tables (same as reload).
flush-status: Clear status variables.
flush-threads: Flush the thread cache.
13. How to kill a hanging MySQL Client Process?
First identify the hanging MySQL client process using the processlist command.
# mysqladmin -u root -ptmppassword processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+----+---------+------+-------+------------------+
| 20 | root | localhost | | Sleep | 64 | | |
| 24 | root | localhost | | Query | 0 | | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+Now, use the kill command and pass the process_id as shown below. To kill multiple process you can pass comma separated process id’s.
# mysqladmin -u root -ptmppassword kill 20
# mysqladmin -u root -ptmppassword processlist
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+----+---------+------+-------+------------------+
| 26 | root | localhost | | Query | 0 | | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+14. How to start and stop MySQL replication on a slave server?
# mysqladmin -u root -ptmppassword stop-slave
Slave stopped
# mysqladmin -u root -ptmppassword start-slave
mysqladmin: Error starting slave: The server is not configured as slave;
fix in config file or with CHANGE MASTER TO15. How to combine multiple mysqladmin commands together?
In the example below, you can combine process-list, status and version command to get all the output together as shown below.
# mysqladmin -u root -ptmppassword process status version
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+----+---------+------+-------+------------------+
| 43 | root | localhost | | Query | 0 | | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+
Uptime: 3135
Threads: 1 Questions: 80 Slow queries: 0 Opens: 15 Flush tables: 3
Open tables: 0 Queries per second avg: 0.25
mysqladmin Ver 8.42 Distrib 5.1.25-rc, for redhat-linux-gnu on i686
Copyright (C) 2000-2006 MySQL AB
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license
Server version 5.1.25-rc-community
Protocol version 10
Connection Localhost via UNIX socket
UNIX socket /var/lib/mysql/mysql.sock
Uptime: 52 min 15 secYou can also use the short form as shown below:
# mysqladmin -u root -ptmppassword pro stat verUse the option -h, to connect to a remote MySQL server and execute the mysqladmin commands as shown below.
# mysqladmin -h 192.168.1.112 -u root -ptmppassword pro stat ver
posted @ 2010-01-21 00:04 alon 阅读(168) 评论(0) 编辑
