uniqueidentifier

问题 I have a process that requires me to identify different machines, and I'm not sure what's the best way to do it. I do not want to save that ID on a text file or something, but I want to generate it from hardware every time I need it (in case the text with the ID gets deleted or something) I've checked UUID, and it seems ok but I'm not sure. I've taken a look at uuid.getNode() , but I have 2 problems with it: One part says "If all attempts to obtain the hardware address fail, we choose a

问题 I have a process that requires me to identify different machines, and I'm not sure what's the best way to do it. I do not want to save that ID on a text file or something, but I want to generate it from hardware every time I need it (in case the text with the ID gets deleted or something) I've checked UUID, and it seems ok but I'm not sure. I've taken a look at uuid.getNode() , but I have 2 problems with it: One part says "If all attempts to obtain the hardware address fail, we choose a

问题 c++ (not c++11) Say i have 100 .cpp files in my project, which currently do some work. All of those files currently include some globals.h file which i can edit easily. I want each of those files to have its own instance of some object, and I also want that instance to have some unique ID of the file in which it is instantiated. In addition, I want those objects to be created by a factory method, and I need the instances to have some way for a user to handle them - meaning they can't be

问题 I'm trying to add a custom property which is a guid, but it gives me this error: System.InvalidCastException: Failed to convert parameter value from a String to a Guid. ---> System.InvalidCastException: Invalid cast from 'System.String' to 'System.Guid'. I specify this in the config: <parameter> <parameterName value="@id" /> <dbType value="Guid" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%X{id}" /> </layout> </parameter> The actual code (snippet) i use is this:

问题 I have a table named Student , contain a column StudentId as GUID , so I used the Uniqueidentifier datatype for that. If I want to get particular record, I get the result by the below query: SELECT * FROM Student WHERE StudentId = '919C3BF9-B081-458C-897D-C0B3FF56AF73' It returns the expected result. But in case if I mistakenly add any extra characters in the end also, it returns the same result. Like the below query: SELECT * FROM Student WHERE StudentId = '919C3BF9-B081-458C-897D

问题 I write websocket chat. How to generate unique id for user? now i use this code: id = new DateTime.now().millisecondsSinceEpoch; is there any more neat solution? 回答1: 1. There is a UUID pub package: http://pub.dartlang.org/packages/uuid example usage: // Generate a v1 (time-based) id uuid.v1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a' // Generate a v4 (random) id uuid.v4(); // -> '110ec58a-a0f2-4ac4-8393-c866d813b8d1' // Generate a v5 (namespace-name-sha1-based) id uuid.v5(uuid.NAMESPACE

问题 I have been using the following method for around a month with no problem. The device ID remained the same even after uninstalls of the app. Recently I noticed that my device ID changed. I have been doing a lot of builds of the app recently on Xcode6. Could this be a cause? I wish I knew exactly when it changed. It caught me by surprise. Do I have anything to worry about when the app goes on the app store? Maybe this is just an Xcode build problem? I am just looking for a simple way to

问题 I have been using the following method for around a month with no problem. The device ID remained the same even after uninstalls of the app. Recently I noticed that my device ID changed. I have been doing a lot of builds of the app recently on Xcode6. Could this be a cause? I wish I knew exactly when it changed. It caught me by surprise. Do I have anything to worry about when the app goes on the app store? Maybe this is just an Xcode build problem? I am just looking for a simple way to

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Creating unique labels in Haskell I've got a datatype Person and some input data from which I will create the Persons. I'd like to have each Person have its own ID (let's say integers [0..]). I could do this with recursion, but since I'm doing this in Haskell, I'd like to understand the monads. The State Monad is probably the best for this job, I suppose? The thing is, I don't really understand lots of things:

问题 Currently in my Node.Js app running on Neo4J I use node-uuid module for giving unique IDs to my database objects. Using uuid.v1() function from that module I get something like 81a0b3d0-e4d0-11e3-ac56-73f5c88681be Now, my requests are quite long, sometimes hundreds of nodes and edges in one query. So you can imagine they become huge, because every node and edge has to have a unique ID. Do you know if I could use a shorter ID system in order to not run into any problems after the number of my