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understood narrowly as the concept in DBMS, not to confuse them with the locking mechanism (row, table, exclusive, shared) provided in the data. In fact, in DBMS, pessimistic lock is implemented by using the lock mechanism provided by the database itself.Below to learn the pessimistic lock and optimistic lock respectively.Pessimistic lock In the relational database management system, pessimistic concurrency control (aka "Pessimistic lock", p

partition layout:# lsblk-fUEFI users should also format the appropriate EFI system partition (take/dev/sdaxy as an example):# Mkfs.vfat-f32/dev/sdaxy# pacman-s DosfstoolsNote: For UEFI boot mode, the disk needs to have GPT partition table and Unified extensible Firmware Interface#efi System partition, FAT32 format, MiB or greater, Gdisk type EF00). In the following demonstration, it is assumed that ESP is mounted to/boot.Select New (or press N) –enter–enter in the first sector to use all remain

return JSON data. it can be on the same host or on a different one (must provide JSONP ). the Autocomplete plugin does not filter the results, instead the request parameter "term" gets added to the URL, which the server-side script shocould use for filtering the results. the data itself can be in the same format as the local data described above.Js Code1. script2. $ (function (){3. $ ("# tags"). autocomplete ({4. source: "search. php ",5. minLength: 2,6. select: function (event, ui ){7. // ui.

= = ' reply, 'Side = ' Left ',PADX = 2m,Pady = 2m,IPADX = 2m,Ipady = 1m)By the way, if you need to use the number "greater than equals" symbol, you should use ">=" instead of "=".In PHP "::" This is called the scope resolution operator, aka domain operatorThe "::" symbol can be thought of as "." In the C language. Similar, and it is more like C + + (Perl):: Class-scoped operators.PHP calls the internal static members of a class, or calls between clas

Source:https://github.com/getify/you-dont-know-js/blob/master/up%20%20going/ch2.md#equalityFalse Values in JS ""(empty string) 0, -0 , NaN (invalid number ) null,undefined Simple Rules Using = =, = = = If either value (aka side) in a comparison could true false is the or value, avoid and use == === . If either value in a comparison could is of these specific values ( 0 , "" , or [] --empty array), avoid == and Use ==

interface.Android.View.Surface: Raw buffer handle managed by screen compositor.3) System Runtime Library native layerAndroid system run native library layer is divided into camera hardware library, PacketVideo framework and surface Library three parts:Camera Hardware Library: Provides a C language library for operating the underlying camera hardware.PacketVideo Frame Library: Multimedia library, based on PacketVideo Opencore, supports a variety of commonly used audio, video format recording and

. Because the contents property is set contentsGravity , it has been stretched to fit the bounds of the layer.If you simply want to enlarge the image of the layer contents , you can do this by using the layer's transform and affineTransform attributes (see Chapter Fifth, "Transforms", which explains it), which is not contengsScale the purpose.contentsScaleProperties are part of a screen mechanism that supports high-resolution (aka hi-dpi or retina). I

definition: In an event-driven environment, such as a browser that continues to seek user attention, the Observer pattern (aka Publisher-subscriber "Publisher-subscriber" mode) is a relationship between the manager and his or her task (specifically, the relationship between its object and its behavior and state).) is a powerful tool. In JavaScript, the essence of this pattern is that you can observe the state of an object in the program and be notifie

Recently full conversion development to Mac OS, with Macvim as IDE. Record some vim basic operations to your own memo.This is said in Common-mode (C-mode, in the Vim aka Normal-mode, is just into vim, can not enter the text of the state) under the movement, the original VI can only move the cursor in the C-mode, In Insert-mode only the input of the text, not the movement of the cursor. Of course, Vim and Elvis's arrow keys are movable freely in either

"; $scope.updated = 0; $scope.$watch('name', function(newValue, oldValue) { if (newValue === oldValue) { return; } // AKA first run $scope.updated++; });}); Index.html Name updated: {{updated}} times. The second parameter of watch accepts two parameters: New Value and old value. We can use them to skip the first execution. Generally, you do not need to skip the first execution, but in this example you need it. Flexible. Example 3: App. js ap

There are three ways to persist iOS data: List of properties (custom property list, Nsuserdefaults) Archive (Nskeyedarchiver) Database (SQLite, Core Data, third-party class libraries, etc.) The following is a main introduction to an archive nskeyedarchiver. Archive (aka serialization), convert objects to bytecode, save them to disk as files, and restore them by unpacking (deserializing) the program as it runs or when it i

Cordova 3.x Foundation (1)--Environment construction (windows/android)The Mobile app is divided into three main categories: Native App,hybrid app,web app. The hybrid app is between the native app and the Web App, which takes into account the native app's good user experience and powerful features, as well as the advantages of rapid web app development across platforms. The disadvantage is that relying on the performance of the Webview,webview of each platform directly determines the performance

(pro/air) and the documents change frequently, the best solution should be to allow the system to automatically back up data in a timely manner through the network. The following describes a simple method. You only need to set up Ubuntu 10 to turn your computer into a Time Machine backup server. (PS: in theory, all Linux systems can be implemented. Because I use Ubuntu 10.10, I will only introduce how to set this system) 1. Install Netatalk Netatalk is a free and open-source AppleTalk communic

Final intdefault_initial_capacity = 1 //aka /*** The maximum capacity, used if a higher value is implicitly specified * by either of the constructors with a Rguments. * Must be a power of */ Static Final intmaximum_capacity = 1 ; /*** The load factor used when none specified in constructor. */ Static Final floatDefault_load_factor = 0.75f; /*** Constructs an empty @paraminitialcapacity The initial capacity *@paramloadfactor the load

attributes can I apply? Let's check them out, one by one.Character AttributesLet's check the character attributes currently available that's can apply to your text:NsfontattributenameThis allows the font of your text. If not specified otherwise, the default is 12-point Helvetica (Neue).NsparagraphstyleattributenameThis allows your to apply multiple attributes (such as alignment, Tab stops and line break mode) to a range of text (aka PA Ragraph).Nsfor

I had some trouble installing Webmin 1.510 on Ubuntu 10.04 LTS Server (aka Lucid). The problem is this Webmin uses a deprecated Perl module (a wrapper around Digest::md5 for users of an ancient MD5 library ) and both Debian and Ubuntu refuse to put it back into their respective repositories. Entirely within their rights, of course, but not so good for us weekend admins who want a painless install process.Okay, so let's get to work. I ' m installing We

Links: blog.jobbole.com/77280/Github.com/kenfox/gc-vizMost developers think of the automatic garbage collector as a matter of course. In fact, this is just a practical feature of the language runtime, designed to simplify our development efforts.But if you try to understand the internal workings of the garbage collector, you'll find it hard to figure out. Unless you're familiar with its workflow and error handling, you'll be overwhelmed by the thousands of implementation details inside.I compile

Architecture, aka Software architecture, is an abstract description of the overall architecture and components of the software that guides the design of large software systems in all aspects.In terms of what a pattern is, the word from architecture is defined as: "Each pattern describes a problem that recurs around us and the core of the solution to that problem. This way, you can use the program again and again without having to do repetitive work. "

on prototype (prototype).The synthesis of multi-party decision making JavaScript become a product of hybridization.In 1996, Microsoft finally realized the importance of the Internet and increased its support for home browser ie, including JScript, so there were two different JavaScript versions on the market at a time. This historical source heralds the untold pain that later programmers have endured to deal with compatibility issues.Finally, in 1997, the European Association of Computer Manufa

}; $ - //Example Usage: - varStudent1 =NewStudent ("Janet", "Applied Physics"); -Student1.sayhello ();//"Hello, I ' m Janet." I ' m studying applied Physics. " AStudent1.walk ();//"I am walking!" +Student1.saygoodbye ();//"goodbye!" the - //Check that instanceof works correctly $Console.log (student1instanceofperson);//true theConsole.log (student1instanceofStudent);//true the the //if on older JavaScript engines without object.create, one can either use a "Polyfill" (