uuid | 易学教程

MySQL UUID primary key - generated by PHP or by MySQL?

阅读更多关于 MySQL UUID primary key - generated by PHP or by MySQL?

问题 I was under the impression that just having MySQL generate the primary key via UUID() would make the key unique across servers, etc. But, there is no way to fetch the last inserted UUID, which requires that an extra select statement be done each time I insert. Is it possible to have PHP generate the exact same UUID() that MySQL would generate? 回答1: No, it's not possible to have PHP generate the exact same UUID() as MySQL because it's a (completely) random number. It sounds like your problem

Foolproof way of differentiating String and UUID

阅读更多关于 Foolproof way of differentiating String and UUID

问题 If I have a string "key:<String || UUID>" is there a way where I can extract the string and differentiate of the part after : is a string or a UUID? Example: in this key:863864947148451183L and key:1234 May be by using the size of a UUID or the number of bytes? 回答1: The only foolproof way is to use UUID.fromString(yourString); It will return an java.lang.IllegalArgumentException: Invalid UUID string: "someString" Handle the exception. The javadoc explains the UUID format. 回答2: Using

A TypeScript GUID class? [closed]

阅读更多关于 A TypeScript GUID class? [closed]

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 2 years ago . Does anyone know of a good, solid, implementation of C# like GUID (UUID) in TypeScript? Could do it myself but figured I'd spare my time if someone else done it before. 回答1: There is an implementation in my TypeScript utilities based on JavaScript GUID generators. Here is the code: class Guid { static newGuid()

UUID 的五个版本

阅读更多关于 UUID 的五个版本

一、概念 1、什么是 UUID UUID 的全称是 Universally Unique Identifier ，中文为通用唯一识别码。构成：由一组 32位数的 16进制数字所构成。格式：以连字号分为五段，表现形式为 8-4-4-4-12 的32个字符，如下所示： xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx 如：30385d15-0a88-42eb-bc43-2c000e9f778c 其中 M 与 N 都有特殊含义： M 表示 UUID版本，目前只有五个版本，即只会出现1，2，3，4，5（下文会介绍这五个版本）数字 N 的一至三个最高有效位表示 UUID 变体，目前只会出现 8，9，a，b 四种情况。 2、UUID 的版本（1）v1 (timestamp) 原理：timestamp + MAC 地址。缺点：机器的MAC地址出厂后不能保证完全唯一，且之后 MAC 地址也可手动修改 MAC 地址的暴露会造成了隐私与安全问题若一台机子上的两个进程同时跑，有可能出现重复问题（2）v2 (timestamp) 原理：基于 v1 的基础上优化了下，更安全。具体优化细节不赘述了。（3）v3 (namespace) 原理：基于 namespace + 输入内容进行 MD5。（4）v4 (random) 原理：基于随机数。

Generate Uuid manually in constructor or via UuidGenerator annotation

阅读更多关于 Generate Uuid manually in constructor or via UuidGenerator annotation

问题 I am switching to Ramsey\Uuid and don't know what is the intended way to generate the Uuids. Either as shown in the examples with an anntoation: /** * @var UuidInterface * * @ORM\Id * @ORM\Column(type="uuid", unique=true) * @ORM\GeneratedValue(strategy="CUSTOM") * @ORM\CustomIdGenerator(class="Ramsey\Uuid\Doctrine\UuidGenerator") */ private $id; public function __construct() { } Or manually in the constructor: /** * @var UuidInterface * * @ORM\Id * @ORM\Column(type="uuid", unique=true) */

How to set cookies for uuid

阅读更多关于 How to set cookies for uuid

问题 I have a website which generates a uuid every time the page is loaded/refreshed. I want to make it so that a certain value remains the same for a period of time using cookies. Does anyone know of a script which can help me? 回答1: Not sure why you are asking for a script, or what the problem here is. To set a cookie, just use: if (empty($_COOKIE["uuid"])) { $uuid = uniqid(); // or use a real UUID setcookie("uuid", $uuid, time()+30*24*60*60, "/"); } else { $uuid = $_COOKIE["uuid"]; } Actually

主键问题

阅读更多关于主键问题

由于在Oracle数据库中，允许没有主键的存在，而hibernate体系又不允许没有主键，这在逻辑上是有冲突的。事实上，表不需要主键。表没有显式键对数据库没有任何影响，因为数据库中的每一行都有一个隐式的唯一数据点，Oracle将其用于存储和某些内部引用，即rowid伪列。rowid是唯一标识数据库中每一行的一段数据。严格来说，没有必要把钥匙放在桌子上。比如现在的项目中，使用的oracle10g数据库有超过1000个系统表，它们没有主键或者说在各自的表上有唯一键。dba和开发人员都可以决定如何在数据库表上创建密钥。然而在开发过程中总是创建主键，这个估计是开发框架导致的，而框架才不管它们是否有用或健全。但作为优秀dba，他们只在有意义的地方创建键。很多时候线上和线下开发是完全隔离开的，线下开发后的测试环境也不可能那么完美的贴合生产环境，笔者的项目中所使用数据库为marridb，而生产环境中使用的数据库为Oracle，这个联调过程中产生的bug也真的是不可多得：），我这边获取到测试数据确实是来自生产环境，然而这个是通过 select 语句而来的，这就直接导致这个表是没有主键的。之后把这些测试数据导入到marridb。现在的情况就是数据库一个没有主键的表，然而通过springboot所创建实体却要求配置主键，这跟数据库中的配置不相符，此外由于实体类中所定义的主键，在数据库中重复出现。

Mongoose and array of ref UUID's does not convert

阅读更多关于 Mongoose and array of ref UUID's does not convert

问题 When using the library mongoose-uuid, I am able to setup UUID types for my schemas, so when I read the data it is in string (utf-8) format and when I save the data it is in UUID ObjectID BSON type 4 format. This works great with top level or flat direct values and ref definitions in my schema. However, when I have a UUID's in an array of ref's in a schema, the array saves to the database correctly, However when it is presented it is in its raw type. Based on the example below you can see

Is Google Drive File ID Unique globally?

阅读更多关于 Is Google Drive File ID Unique globally?

问题 Is Google Drive File ID is unique across globe. Is there chance that UUID generated using NSUUID class will be same as Google drive File ID? FYI:This is not duplicate of 'Are google docs/drive resource_id's globally unique' 回答1: The way we generate IDs are quite different than UUID generation and the canonical form of Drive generated IDs differ from v1/2/3/4/5 UUIDs. It's not possible you will see a collision. 回答2: I would bet a great deal of money that Google does not check to ensure that

Boost compile error on converting UUID to string using boost::lexical_cast

阅读更多关于 Boost compile error on converting UUID to string using boost::lexical_cast

问题 I have this code which is based on several posts in SO: boost::uuids::uuid uuid = boost::uuids::random_generator()(); auto uuidString= boost::lexical_cast<std::string>(uuid); but when I am compiling this code, I am getting this error: Source type is neither std::ostream`able nor std::wostream`able C:\Local\boost\boost\lexical_cast\detail\converter_lexical.hpp How can I fix this error? 回答1: You're missing the include, I guess: Live On Coliru #include <boost/lexical_cast.hpp> #include <boost