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  • Which database should I use for best performance

    - by _simon_
    Hello, I am working in Visual Studio 2005, .NET 2.0. I need to write an application, which listens on COM port and saves incoming data to a database. Main feature: save incoming data (series of 13-digits numbers), if this number allready exists, then mark it as double. For example, there could be these records in database: 0000000000001 OK 0000000000002 OK 0000000000002 Double 0000000000003 OK 0000000000004 OK I could use SQL database, but I don't know if it is fast enough... Database should be able to store up to 10.000.000 records and write up to 100 records per minute (so it needs to check 100 times per minute if this record allready exists). Which database should I use? Maybe the whole database would need to be in RAM. Where could I learn more about this? Thanks

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  • The best way to structure this database?

    - by James P
    At the moment I'm doing this: gems(id, name, colour, level, effects, source) id is the primary key and is not auto-increment. A typical row of data would look like this: id => 40153 name => Veiled Ametrine colour => Orange level => 80 effects => +12 sp, +10 hit source => Ametrine (Some of you gamers might see what I'm doing here :) ) But I realise this could be sorted a lot better. I have studied database relationships and secondary keys in my A-Level computing class but never got as far as to set one up properly. I just need help with how this database should be organised, like what tables should have what data with what secondary and foreign keys? I was thinking maybe 3 tables: gem, effects, source. Which then have relationships to each other? Can anyone shed some light on this? Is a complex way like I'm proposing really the way to go or should I just carry on with what I'm doing? Cheers.

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  • Global State and Singletons Dependency injection

    - by Manu
    this is a problem i face lot of times when i am designing a new app i'll use a sample problem to explain this think i am writing simple game.so i want to hold a list of players. i have few options.. 1.use a static field in some class private static ArrayList<Player> players = new ArrayList<Integer>(); public Player getPlayer(int i){ return players.get(i); } but this a global state 2.or i can use a singleton class PlayerList{ private PlayerList instance; private PlayerList(){...} public PlayerList getInstance() { if(instance==null){ ... } return instance; } } but this is bad because it's a singleton 3.Dependency injection class Game { private PlayerList playerList; public Game(PlayerList list) { this.list = list; } public PlayerList getPlayerList() { return playerList; } } this seems good but it's not, if any object outside Game need to look at PlayerList (which is the usual case) i have to use one of the above methods to make the Game class available globally. so I just add another layer to the problem. didn't actually solve anything. what is the optimum solution ? (currently i use Singleton approach)

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  • What CSS do I need to make my site more responsive?

    - by user2938757
    My site is: http://library.skybundle.com I feel like I almost have a responsive site. I did all the CSS styling myself. It is a Wordpress site but I completely edited the CSS of the original theme, so it is night-and-day different than it used to be. The original theme was mostly just for a canvas for me to work with, since I am not an expert in PHP and we wanted a Wordpress site for easy editing later on. Thanks to stackoverflow, I now have a footer that sticks to the bottom of every page and everything mostly looks good -- the way we want it anyway. The only thing missing now is the we want browser windows on MOBILE devices, such as on an iPhone, to automatically adjust the layout of the content in the body (wrapper). For example, on the main page (library.skybundle.com), I would like those two big icons two become vertically aligned as soon as the browser window sizes to a small, mostly vertical size, like that of a mobile phone. Take this site, for example: http://freedomsoundproductions.securesb.net/ This is what we would like it to do. So one a page with a sidebar, the content to the right of the sidebar should basically jump into the same "column" as the left sidebar and form one single long column. Just like in the example site above. This should all be possible via CSS. People in other forums seem to want me to use jQuery and stuff, but I can only use CSS, and I know that this must be possible without having to resort to jQuery, HTML, or other code.

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  • How to make 2 incompatible types, but with the same members, interchangeable?

    - by Quigrim
    Yesterday 2 of the guys on our team came to me with an uncommon problem. We are using a third-party component in one of our winforms applications. All the code has already been written against it. They then wanted to incorporate another third-party component, by the same vender, into our application. To their delight they found that the second component had the exact same public members as the first. But to their dismay, the 2 components have completely separate inheritance hierarchies, and implement no common interfaces. Makes you wonder... Well, makes me wonder. An example of the problem: public class ThirdPartyClass1 { public string Name { get { return "ThirdPartyClass1"; } } public void DoThirdPartyStuff () { Console.WriteLine ("ThirdPartyClass1 is doing its thing."); } } public class ThirdPartyClass2 { public string Name { get { return "ThirdPartyClass2"; } } public void DoThirdPartyStuff () { Console.WriteLine ("ThirdPartyClass2 is doing its thing."); } } Gladly they felt copying and pasting the code they wrote for the first component was not the correct answer. So they were thinking of assigning the component instant into an object reference and then modifying the code to do conditional casts after checking what type it was. But that is arguably even uglier than the copy and paste approach. So they then asked me if I can write some reflection code to access the properties and call the methods off the two different object types since we know what they are, and they are exactly the same. But my first thought was that there goes the elegance. I figure there has to be a better, graceful solution to this problem.

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  • Interesting or unique types encountered?

    - by user318904
    What is the most strange or unique type you have seen in a programming language? I was thinking the other day about a "random variable", ie whenever it is evaluated it yields a random value from some domain. It would require some runtime trickery. Also I bet there can be some interesting mapping of regular expressions into a type system. It does not necessarily have to be a built in or primitive type, but some random class that implements a domain specific type won't really be interesting just unique.

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  • db optimization - have a total field or query table?

    - by Dorian Fife
    I have an app where users get points for actions they perform - either 1 point for an easy action or 2 for a difficult one. I wish to display to the user the total number of points he got in my app and the points obtained this week (since Monday at midnight). I have a table that records all actions, along with their time and number of points. I have two alternatives and I'm not sure which is better: Every time the user sees the report perform a query and sum the points the user got Add two fields to each user that records the number of points obtained so far (total and weekly). The weekly points value will be set to 0 every Monday at midnight. The first option is easier, but I'm afraid that as I'll get many users and actions queries will take a long time. The second option bares the risk of inconsistency between the table of actions and the summary values. I'm very interested in what you think is the best alternative here. Thanks, Dorian

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  • Multiple column foreign key contraints

    - by eugene4968
    I want to setup table constraints for the following scenario and I’m not sure how to do it or if it’s even possible in SQL Server 2005. I have three tables A,B,C. C is a child of B. B will have a optional foreign key(may be null) referencing A. For performance reasons I also want table C to have the same foreign key reference to table A. The constraint on table C should be that C must reference its parent (B) and also have the same foreign key reference to A as its parent. Anyone have any thoughts on how to do this?

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  • Does database affect classes?

    - by satyanarayana
    I had created one class User and UserDAOImpl class for querying DB using class User. As there is one table to be queried, these two classes are sufficient for me. What if there is a case where new fields are to be added to that one table is to be divided into 3 tables( user_info, user_profile and user_address) to store user? As new fields are added, I need to change classes User and UserDAOImpl, it seems these two are not sufficient. It seems database changes affect my classes. In this case, do I need to divide class User into 3 classes as tables are changes? Can any one suggest me how can I solve this without making too many changes?

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  • how to store data with many categories and many properties efficiently?

    - by Mickey Shine
    We have a large number of data in many categories with many properties, e.g. category 1: Book properties: BookID, BookName, BookType, BookAuthor, BookPrice category 2: Fruit properties: FruitID, FruitName, FruitShape, FruitColor, FruitPrice We have many categories like book and fruit. Obviously we can create many tables for them (MySQL e.g.), and each category a table. But this will have to create too many tables and we have to write many "adapters" to unify manipulating data. The difficulties are: 1) Every category has different properties and this results in a different data structure. 2) The properties of every categoriy may have to be changed at anytime. 3) Hard to manipulate data if each category a table (too many tables) How do you store such kind of data?

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  • What is the sense of "Feature Oriented Programming" (FOP) in C++, and would it make sense in Java an

    - by ivan_ivanovich_ivanoff
    Hello! Sadly, I can't remember where I read it, but... ...in C++ you can derive a class from a template parameter. Im pretty sure it was called Feature Oriented Programming (FOP) and meant to be somehow useful. It was something like: template <class T> class my_class : T { // some very useful stuff goes here ;) } My questions about this: What is the sense of such pattern? Since this it not possible in Java / C#, how this pattern is achieved in these languages? Can it be expected to be implemented in Java / C# one day? (Well, first Java would need to get rid of type erasure) EDIT: I'm really not talking about generics in Java / C# (where you can't derive a class from a generic type parameter)

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  • How to simplify the code?

    - by Tattat
    I have objectA, and objectB.... also I have objectAs, and objectBs. the objectA is only have the init method, and ObjectAs have somethings like this: #import "ObjectAs.h" @implementation ObjectAs @synthesize objectAs; -(id) init{ if( (self=[super init])) { self.objectAs = [[NSMutableArray alloc] init]; } return self; } -(int)getObjectAsNumber{ return [self.objectAs count]; } -(void)addObjectA:(ObjectA *)newObjectA{ [self.objectAs addObject:newObjectA]; } -(id)getObjectAByIdx:(int)objectAIdx{ return [self.objectAs objectAtIndex:objectAIdx]; } -(void)dealloc{ [super dealloc]; [objectAs release]; } @end The objectBs have similar have, I know that I can copy and paste, and replace it. Is there any way to simplify the objectBs, and objectAs? thz a lot.

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  • How to create Multiple images with hyperlinks

    - by Jasl
    I have a psd image with me. This image has been created combining multiple images. I want that each of this multiple images must have a seperate alt tag and a hyperlink. When the user clicks on it, he/she should be taken to the that url. How can I do it. Please suggest me all options like open source or online tools etc.

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  • What is the business case for a dependency injection (DI) framework?

    - by kalkie
    At my company we want to start using a dependency injection (DI) framework for managing our dependencies. I have some difficulty with explaining the business value of such a framework. Currently I have come up with these reasons. Less source code, delete all the builder patterns in the code. Increase in flexibility. Easier to switch dependencies. Better separation of concern. The framework is responsible for creating instances instead of our code. Has anybody else had to persuade management? How did you do that? What reasons did you use?

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  • MSSQL Server using multiple ID Numbers

    - by vincer
    I have an web application that creates printable forms, these forms have a unique number on them, the problem is I have 2 forms that separate numbers need to be created for them. ie) Form1- Numbered 2000000-2999999 Form2- Numbered 3000000-3999999 dbo.test2 - is my form information table Tsel - is my autoinc table for the 3000000 series numbers Tadv - is my autoinc table for the 2000000 series numbers What I have done is create 2 tables with just autoinc row (one for 2000000 series numbers and one for 3000000 series numbers), I then created a trigger to add a record to the coresponding table, read back the autoinc number and add it to my table that stores the form information including the just created autoinc number for the right series of forms. Although it does work, I'm concerned that the numbers will get messed up under load. I'm not sure the @@IDENTITY will always return the right value when many people are using the system. (I cannot have duplicates and I need to use the numbering form show above. Thanks for any help See code below. ** TRIGGER ** CREATE TRIGGER MAKEANID2 ON dbo.test2 AFTER INSERT AS SET NOCOUNT ON declare @someid int declare @someid2 int declare @startfrom int declare @test1 varchar(10) select @someid=@@IDENTITY select @test1 = (Select name1 from test2 where sysid = @someid ) if @test1 = 'select' begin insert into Tsel Default values select @someid2 = @@IDENTITY end if @test1 = 'adv' begin insert into Tadv Default values select @someid2 = @@IDENTITY end update test2 set name2=(@someid2) where sysid = @someid SET NOCOUNT OFF

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  • How do I manipulate a tree of immutable objects?

    - by Frederik
    I'm building an entire application out of immutable objects so that multi-threading and undo become easier to implement. I'm using the Google Collections Library which provides immutable versions of Map, List, and Set. My application model looks like a tree: Scene is a top-level object that contains a reference to a root Node. Each Node can contain child Nodes and Ports. An object graph might look like this: Scene | +-- Node | +-- Node | +- Port +-- Node | +- Port +- Port If all of these objects are immutable, controlled by a top-level SceneController object: What is the best way to construct this hierarchy? How would I replace an object that is arbitrarily deep in the object tree? Is there a way to support back-links, e.g. a Node having a "parent" attribute?

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  • Several C# Language Questions

    - by Water Cooler v2
    1) What is int? Is it any different from the struct System.Int32? I understand that the former is a C# alias (typedef or #define equivalant) for the CLR type System.Int32. Is this understanding correct? 2) When we say: IComparable x = 10; Is that like saying: IComparable x = new System.Int32(); But we can't new a struct, right? or in C like syntax: struct System.In32 *x; x=>someThing = 10; 3) What is String with a capitalized S? I see in Reflector that it is the sealed String class, which, of course, is a reference type, unlike the System.Int32 above, which is a value type. What is string, with an uncapitalized s, though? Is that also the C# alias for this class? Why can I not see the alias definitions in Reflector? 4) Try to follow me down this subtle train of thought, if you please. We know that a storage location of a particular type can only access properties and members on its interface. That means: Person p = new Customer(); p.Name = "Water Cooler v2"; // legal because as Name is defined on Person. but // illegal without an explicit cast even though the backing // store is a Customer, the storage location is of type // Person, which doesn't support the member/method being // accessed/called. p.GetTotalValueOfOrdersMade(); Now, with that inference, consider this scenario: int i = 10; // obvious System.object defines no member to // store an integer value or any other value in. // So, my question really is, when the integer is // boxed, what is the *type* it is actually boxed to. // In other words, what is the type that forms the // backing store on the heap, for this operation? object x = i; Update Thank you for your answers, Eric Gunnerson and Aaronought. I'm afraid I haven't been able to articulate my questions well enough to attract very satisfying answers. The trouble is, I do know the answers to my questions on the surface, and I am, by no means, a newbie programmer. But I have to admit, a deeper understanding to the intricacies of how a language and its underlying platform/runtime handle storage of types has eluded me for as long as I've been a programmer, even though I write correct code.

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  • How to implement the API/SPI Pattern in Java?

    - by Adam Tannon
    I am creating a framework that exposes an API for developers to use: public interface MyAPI { public void doSomeStuff(); public int getWidgets(boolean hasRun); } All the developers should have to do is code their projects against these API methods. I also want them to be able to place different "drivers"/"API bindings" on the runtime classpath (the same way JDBC or SLF4J work) and have the API method calls (doSomeStuff(), etc.) operate on different 3rd party resources (files, servers, whatever). Thus the same code and API calls will map to operations on different resources depending on what driver/binding the runtime classpath sees (i.e. myapi-ftp, myapi-ssh, myapi-teleportation). How do I write (and package) an SPI that allows for such runtime binding, and then maps MyAPI calls to the correct (concrete) implementation? In other words, if myapi-ftp allows you to getWidgets(boolean) from an FTP server, how would I could this up (to make use of both the API and SPI)? Bonus points for concrete, working Java code example! Thanks in advance!

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  • HTML columns or rows for form layout?

    - by Valera
    I'm building a bunch of forms that have labels and corresponding fields (input element or more complex elements). Labels go on the left, fields go on the right. Labels in a given form should all be a specific width so that the fields all line up vertically. There are two ways (maybe more?) of achieving this: Rows: Float each label and each field left. Put each label and field in a field-row div/container. Set label width to some specific number. With this approach labels on different forms will have different widths, because they'll depend on the width of the text in the longest label. Columns: Put all labels in one div/container that's floated left, put all fields in another floated left container with padding-left set. This way the labels and even the label container don't need to have their widths set, because the column layout and the padding-left will uniformly take care of vertically lining up all the fields. So approach #2 seems to be easier to implement (because the widths don't need to be set all the time), but I think it's also less object oriented, because a label and a field that goes with that label are not grouped together, as they are in approach #1. Also, if building forms dynamically, approach #2 doesn't work as well with functions like addRow(label, field), since it would have to know about the label and the field containers, instead of just creating/adding one field-row element. Which approach do you think is better? Is there another, better approach than these two?

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