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  • Any tips of how to handle hierarchical trees in relational model?

    - by George
    Hello all. I have a tree structure that can be n-levels deep, without restriction. That means that each node can have another n nodes. What is the best way to retrieve a tree like that without issuing thousands of queries to the database? I looked at a few other models, like flat table model, Preorder Tree Traversal Algorithm, and so. Do you guys have any tips or suggestions of how to implement a efficient tree model? My objective in the real end is to have one or two queries that would spit the whole tree for me. With enough processing i can display the tree in dot net, but that would be in client machine, so, not much of a big deal. Thanks for the attention

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  • c# - pull records from database without timeout

    - by BhejaFry
    Hi folks, i have a sql query with multiple joins & it pulls data from a database for processing. This is supposed to be running on some scheduled basis. So day 1, it might pull 500, day 2 say 400. Now, if the service is stopped for some reason & the data not processed, then on day3 there could be as much as 1000 records to process. This is causing timeout on the sql query. How best to handle this situation without causing timeout & gradually reducing workload to process? TIA

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  • Is it possible to create a domain model for legacy code without refactoring?

    - by plaureano
    I currently have a client that wants me to 'abstract' out a domain model from the existing code but they specifically said that I shouldn't refactor the existing code itself. My question is 1) whether or not this is advisable and 2) what techniques would you apply in this scenario if you can't refactor the code yet they expect you to come up with a model for it? (EDIT: I can't quite put my finger on it, but somehow, not being able to refactor in this case just feels wrong. Has anyone else run into this type of scenario?)

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  • Upgrade .NET 1.1 WinForm/Service to what?

    - by Conor
    Hi Folks, We have a current WinForm/Windows Service running in .NET 1.1 out on various customer sites that is getting data from internal systems, transforming it and then calling a Web Service synchronously. This client app will no longer work in Vista or Windows 7 etc.. and its time to update!! I was looking for ideas on what I could do here, I didn't write the App and I have the Business team telling me they want the world but I need to be realistic :) Things the service must be able to do: - Handle multiple formats from internal system and transform to a schema SAP, ERP etc.. - Run silently and just work on customer sites (it does currently albeit .NET 1.1) - The Customers are unable to call our web service from their sites as they are not technical enough. - Upgrade it's self when updates occur (currently don't have this capability) Is there anything I can do here other than upgrade the service to run in .NET and add a few more transformation capabilities e..g they want the customer to be able to give us a flat file, an xml file, a csv and the service transforms it and calls the Web Service? I was hoping in this day and age we could use the Web, but automating this 100% rules it out in my eyes? I could be totally wrong!! Any help would be gratefully appreciated! Cheers. Conor

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  • Vertex Buffers in opengl

    - by JB
    I'm making a small 3d graphics game/demo for personal learning. I know d3d9 and quite a bit about d3d11 but little about opengl at the moment so I'm intending to abstract out the actual rendering of the graphics so that my scene graph and everything "above" it needs to know little about how to actually draw the graphics. I intend to make it work with d3d9 then add d3d11 support and finally opengl support. Just as a learning exercise to learn about 3d graphics and abstraction. I don't know much about opengl at this point though, and don't want my abstract interface to expose anything that isn't simple to implement in opengl. Specifically I'm looking at vertex buffers. In d3d they are essentially an array of structures, but looking at the opengl interface the equivalent seems to be vertex arrays. However these seem to be organised rather differently where you need a separate array for vertices, one for normals, one for texture coordinates etc and set the with glVertexPointer, glTexCoordPointer etc. I was hoping to be able to implement a VertexBuffer interface much like the the directx one but it looks like in d3d you have an array of structures and in opengl you need a separate array for each element which makes finding a common abstraction quite hard to make efficient. Is there any way to use opengl in a similar way to directx? Or any suggestions on how to come up with a higher level abstraction that will work efficiently with both systems?

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  • Planning a database app

    - by ChrisC
    I am in the planning stages of a database app for personal use. I have a good bit of the database structure planned, but as I think about how I'm going to write the program, it made me wonder if I'm doing this in the right order. Which should I be planning first, the db structure or the classes?

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  • Database Modelling - Conceptually different entities but with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has MarketPriceDataSetId (foreign key to parent table) StartDate EndDate SimulationItemId ForwardPrice PoolPriceForecastEntry has PoolPriceForecastDataSetId (foreign key to parent table) StartDate EndDate SimulationItemId ForecastPoolPrice If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

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  • Autmatically create table on MySQL server based on date?

    - by Anthony
    Is there an equivalent to cron for MySQL? I have a PHP script that queries a table based on the month and year, like: SELECT * FROM data_2010_1 What I have been doing until now is, every time the script executes it does a query for the table, and if it exists, does the work, if it doesn't it creates the table. I was wondering if I can just set something up on the MySQL server itself that will create the table (based on a default table) at the stroke of midnight on the first of the month. Update Based on the comments I've gotten, I'm thinking this isn't the best way to achieve my goal. So here's two more questions: If I have a table with thousands of rows added monthly, is this potentially a drag on resources? If so, what is the best way to partition this table, since the above is verboten? What are the potential problems with my home-grown method I originally thought up?

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  • Truly declarative language?

    - by gjvdkamp
    Hi all, Does anyone know of a truly declarative language? The behaviour I'm looking for is kind of what Excel does, where I can define variables and formulas, and have the formula's result change when the input changes (without having set the answer again myself) The behaviour I'm looking for is best shown with this pseudo code: X = 10 // define and assign two variables Y = 20; Z = X + Y // declare a formula that uses these two variables X = 50 // change one of the input variables ?Z // asking for Z should now give 70 (50 + 20) I've tried this in a lot of languages like F#, python, matlab etc, but every time i try this they come up with 30 instead of 70. Wich is correct from an imperative point of view, but i'm looking for a more declerative behaviour if you know what i mean. And this is just a very simple calculation. When things get more difficult it should handle stuff like recursion and memoization automagically. The code below would obviously work in C# but it's just so much code for the job, i'm looking for something a bit more to the point without all that 'technical noise' class BlaBla{ public int X {get;set;} // this used to be even worse before 3.0 public int Y {get;set;} public int Z {get{return X + Y;}} } static void main(){ BlaBla bla = new BlaBla(); bla.X = 10; bla.Y = 20; // can't define anything here bla.X = 50; // bit pointless here but I'll do it anyway. Console.Writeline(bla.Z);// 70, hurray! } This just seems like so much code, curly braces and semicolons that add nothing. Is there a language/ application (apart from Exel) that does this? Maybe I'm no doing it right in the mentioned langauges, or I've completely missed an app that does just this. I prototyped a language/ application that does this (along with some other stuff) and am thinking of productizing it. I just can't believe it's not there yet. Don't want to waste my time. Thanks in advance, Gert-Jan

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  • Implementing the procducer-consumer with .NET 4.0 new

    - by bitbonk
    With alle the new paralell programming features in .NET 4.0, what would be a a simple and fast way to implement the producer-consumer pattern (where at least one thread is producing and enqueuing task items and one other thread executes (dequeues) these tasks). Can we benfit from all these new APIs? What is your preferred implementation of this pattern?

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  • Data Modeling Help - Do I add another table, change existing table's usage, or something else?

    - by StackOverflowNewbie
    Assume I have the following tables and relationships: Person - Id (PK) - Name A Person can have 0 or more pets: Pet - Id (PK) - PersonId (FK) - Name A person can have 0 or more attributes (e.g. age, height, weight): PersonAttribute _ Id (PK) - PersonId (FK) - Name - Value PROBLEM: I need to represent pet attributes, too. As it turns out, these pet attributes are, in most cases, identical to the attributes of a person (e.g. a pet can have an age, height, and weight too). How do I represent pet attributes? Do I create a PetAttribute table? PetAttribute Id (PK) PetId (FK) Name Value Do I change PersonAttribute to GenericAttribute and have 2 foreign keys in it - one connecting to Person, the other connecting to Pet? GenericAttribute Id (PK) PersonId (FK) PetId (FK) Name Value NOTE: if PersonId is set, then PetId is not set. If PetId is set, PersonId is not set. Do something else?

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  • Primary key/foreign Key naming convention

    - by Jeremy
    In our dev group we have a raging debate regarding the naming convention for Primary and Foreign Keys. There's basically two schools of thought in our group: 1) Primary Table (Employee) Primary Key is called ID Foreign table (Event) Foreign key is called EmployeeID 2) Primary Table (Employee) Primary Key is called EmployeeID Foreign table (Event) Foreign key is called EmployeeID I prefer not to duplicate the name of the table in any of the columns (So I prefer option 1 above). Conceptually, it is consisted with a lot of the recommended practices in other languages, where you don't use the name of the object in its property names. I think that naming the foreign key EmployeeID (or Employee_ID might be better) tells the reader that it is the ID column of the Employee Table. Some others prefer option 2 where you name the primary key prefixed with the table name so that the column name is the same throughout the database. I see that point, but you now can not visually distinguish a primary key from a foreign key. Also, I think it's redundant to have the table name in the column name, because if you think of the table as an entity and a column as a property or attribute of that entity, you think of it as the ID attribute of the Employee, not the EmployeeID attribute of an employee. I don't go an ask my coworker what his PersonAge or PersonGender is. I ask him what his Age is. So like I said, it's a raging debate and we go on and on and on about it. I'm interested to get some new perspective.

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  • Using inheritance and polymorphism to solve a common game problem

    - by Barry Brown
    I have two classes; let's call them Ogre and Wizard. (All fields are public to make the example easier to type in.) public class Ogre { int weight; int height; int axeLength; } public class Wizard { int age; int IQ; int height; } In each class I can create a method called, say, battle() that will determine who will win if an Ogre meets and Ogre or a Wizard meets a Wizard. Here's an example. If an Ogre meets an Ogre, the heavier one wins. But if the weight is the same, the one with the longer axe wins. public Ogre battle(Ogre o) { if (this.height > o.height) return this; else if (this.height < o.height) return o; else if (this.axeLength > o.axeLength) return this; else if (this.axeLength < o.axeLength) return o; else return this; // default case } We can make a similar method for Wizards. But what if a Wizard meets an Ogre? We could of course make a method for that, comparing, say, just the heights. public Wizard battle(Ogre o) { if (this.height > o.height) return this; else if (this.height < o.height) return o; else return this; } And we'd make a similar one for Ogres that meet Wizard. But things get out of hand if we have to add more character types to the program. This is where I get stuck. One obvious solution is to create a Character class with the common traits. Ogre and Wizard inherit from the Character and extend it to include the other traits that define each one. public class Character { int height; public Character battle(Character c) { if (this.height > c.height) return this; else if (this.height < c.height) return c; else return this; } } Is there a better way to organize the classes? I've looked at the strategy pattern and the mediator pattern, but I'm not sure how either of them (if any) could help here. My goal is to reach some kind of common battle method, so that if an Ogre meets an Ogre it uses the Ogre-vs-Ogre battle, but if an Ogre meets a Wizard, it uses a more generic one. Further, what if the characters that meet share no common traits? How can we decide who wins a battle?

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  • Should I use custom exceptions to control the flow of application?

    - by bonefisher
    Is it a good practise to use custom business exceptions (e.g. BusinessRuleViolationException) to control the flow of user-errors/user-incorrect-inputs??? The classic approach: I have a web service, where I have 2 methods, one is the 'checker' (UsernameAlreadyExists()) and the other one is 'creator' (CreateUsername())... So if I want to create a username, I have to do 2 roundtrips to webservice, 1.check, 2.if check is OK, create. What about using UsernameAlreadyExistsException? So I call only the 2. web service method (CrateUsername()), which contains the check and if not successfull, it throws the UsernameAlreadyExistsException. So the end goal is to have only one round trip to web service and the checking can be contained also in other web service methods (so I avoid calling the UsernameAlreadyExists() all the times..). Furthermore I can use this kind of business error handling with other web service calls completely avoiding the checking prior the call.

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  • What to name column in database table that holds versioning number

    - by rwmnau
    I'm trying to figure out what to call the column in my database table that holds an INT to specific "record version". I'm currently using "RecordOrder", but I don't like that, because people think higher=newer, but the way I'm using it, lower=newer (with "1" being the current record, "2" being the second most current, "3" older still, and so on). I've considered "RecordVersion", but I'm afraid that would have the same problem. Any other suggestions? "RecordAge"? I'm doing this because when I insert into the table, instead of having to find out what version is next, then run the risk of having that number stolen from me before I write, I just insert insert with a "RecordOrder" of 0. There's a trigger on the table AFTER INSERT that increments all the "RecordOrder" numbers for that key by 1, so the record I just inserted becomes "1", and all others are increased by 1. That way, you can get a person's current record by selection RecordOrder=1, instead of getting the MAX(RecordOrder) and then selecting that. PS - I'm also open to criticism about why this is a terrible idea and I should be incrementing this index instead. This just seemed to make lookups much easier, but if it's a bad idea, please enlighten me! Some details about the data, as an example: I have the following database table: CREATE TABLE AmountDue ( CustomerNumber INT, AmountDue DECIMAL(14,2), RecordOrder SMALLINT, RecordCreated DATETIME ) A subset of my data looks like this: CustomerNumber Amountdue RecordOrder RecordCreated 100 0 1 2009-12-19 05:10:10.123 100 10.05 2 2009-12-15 06:12:10.123 100 100.00 3 2009-12-14 14:19:10.123 101 5.00 1 2009-11-14 05:16:10.123 In this example, there are three rows for customer 100 - they owed $100, then $10.05, and now they owe nothing. Let me know if I need to clarify it some more. UPDATE: The "RecordOrder" and "RecordCreated" columns are not available to the user - they're only there for internal use, and to help figure out which is the current customer record. Also, I could use it to return an appropriately-ordered customer history, though I could just as easily do that with the date. I can accomplish the same thing as an incrementing "Record Version" with just the RecordCreated date, I suppose, but that removes the convenience of knowing that RecordOrder=1 is the current record, and I'm back to doing a sub-query with MAX or MIN on the DateTime to determine the most recent record.

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  • Why should GoTos be bad?

    - by lisn
    I'm using gotos and a lot of them. C++, PHP or COBOL - I use them on nearly all occasions where everybody else would use functions or even classes. Yet my code is Clear Maintainable Bug-free Fast So why does everybody I meet tell me about how bad gotos are? Are there any facts that show that they are "bad"?

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  • JavaScript inheritance

    - by Tower
    Hi, Douglas Crockford seems to like the following inheritance approach: if (typeof Object.create !== 'function') { Object.create = function (o) { function F() {} F.prototype = o; return new F(); }; } newObject = Object.create(oldObject); It looks OK to me, but how does it differ from John Resig's simple inheritance approach? Basically it goes down to newObject = Object.create(oldObject); versus newObject = Object.extend(); And I am interested in theories. Implementation wise there does not seem to be much difference.

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  • Good tool to visualise database schema?

    - by Mat
    Are there any good tools for visualising a pre-existing database schema? I'm using MySQL if it matters. I'm currently using MySQL Workbench to process an SQL create script dump, but it's clunky, slow and a manual process to drag all the tables about (which would be okay if it wasn't so slow).

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  • How to leverage Spring Integration in a real-world JMS distributed architecture?

    - by ngeek
    For the following scenario I am looking for your advices and tips on best practices: In a distributed (mainly Java-based) system with: many (different) client applications (web-app, command-line tools, REST API) a central JMS message broker (currently in favor of using ActiveMQ) multiple stand-alone processing nodes (running on multiple remote machines, computing expensive operations of different types as specified by the JMS message payload) How would one best apply the JMS support provided by the Spring Integration framework to decouple the clients from the worker nodes? When reading through the reference documentation and some very first experiments it looks like the configuration of an JMS inbound adapter inherently require to use a subscriber, which in a decoupled scenario does not exist. Small side note: communication should happen via JMS text messages (using a JSON data structure for future extensibility).

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  • Initialization of components with interdependencies - possible antipattern?

    - by Rosarch
    I'm writing a game that has many components. Many of these are dependent upon one another. When creating them, I often get into catch-22 situations like "WorldState's constructor requires a PathPlanner, but PathPlanner's constructor requires WorldState." Originally, this was less of a problem, because references to everything needed were kept around in GameEngine, and GameEngine was passed around to everything. But I didn't like the feel of that, because it felt like we were giving too much access to different components, making it harder to enforce boundaries. Here is the problematic code: /// <summary> /// Constructor to create a new instance of our game. /// </summary> public GameEngine() { graphics = new GraphicsDeviceManager(this); Components.Add(new GamerServicesComponent(this)); //Sets dimensions of the game window graphics.PreferredBackBufferWidth = 800; graphics.PreferredBackBufferHeight = 600; graphics.ApplyChanges(); IsMouseVisible = true; screenManager = new ScreenManager(this); //Adds ScreenManager as a component, making all of its calls done automatically Components.Add(screenManager); // Tell the program to load all files relative to the "Content" directory. Assets = new CachedContentLoader(this, "Content"); inputReader = new UserInputReader(Constants.DEFAULT_KEY_MAPPING); collisionRecorder = new CollisionRecorder(); WorldState = new WorldState(new ReadWriteXML(), Constants.CONFIG_URI, this, contactReporter); worldQueryUtils = new WorldQueryUtils(worldQuery, WorldState.PhysicsWorld); ContactReporter contactReporter = new ContactReporter(collisionRecorder, worldQuery, worldQueryUtils); gameObjectManager = new GameObjectManager(WorldState, assets, inputReader, pathPlanner); worldQuery = new DefaultWorldQueryEngine(collisionRecorder, gameObjectManager.Controllers); gameObjectManager.WorldQueryEngine = worldQuery; pathPlanner = new PathPlanner(this, worldQueryUtils, WorldQuery); gameObjectManager.PathPlanner = pathPlanner; combatEngine = new CombatEngine(worldQuery, new Random()); } Here is an excerpt of the above that's problematic: gameObjectManager = new GameObjectManager(WorldState, assets, inputReader, pathPlanner); worldQuery = new DefaultWorldQueryEngine(collisionRecorder, gameObjectManager.Controllers); gameObjectManager.WorldQueryEngine = worldQuery; I hope that no one ever forgets that setting of gameObjectManager.WorldQueryEngine, or else it will fail. Here is the problem: gameObjectManager needs a WorldQuery, and WorldQuery needs a property of gameObjectManager. What can I do about this? Have I found an anti-pattern?

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  • Strategy to structure a search index in a relational database

    - by neilc
    I am interested in suggestions for building an efficient and robust structure for indexing products in a new database I am building (i'm using MySql) When a product is entered through the form there are three parts I am interested in indexing for searching purposes. The product title The product description Tags The most important is title, followed by tags, followed by the description. I was thinking of using the following structure CREATE TABLE `searchindex` ( `id` INT NOT NULL , `word` VARCHAR( 255 ) NOT NULL , `weighting` INT NOT NULL , `product_id` INT NOT NULL , PRIMARY KEY ( `id` ) ) Then each time a product is created I would split apart the title, description and tags (removing common words) and award them a weighting. Then it is trivial to select out the words and corresponding products and order them by weighting. Is there a better way to do this? I would be worried that this strategy would slow down over time and as the database filled up.

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  • Building a professional company website

    - by Sphynx
    Hi fellows, I want to create a professional website for my company. I'm not a designer. I know some html/css, but I don't have much experience making up advanced pages and layouts. I'd expect public area, with various articles, and a "customer zone", accessible via username and password, where clients will be able to track their orders and download files. It needs to look very modern. I don't want to use website templates, because they're too simple. I know some Wordpress, but that's mostly for blogs, and anyways you need to find a right theme besides the CMS itself... Is there any alternative solution, some kind of framework for building such portals? Preferably a system that doesn't require designer skills. Thanks!

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  • When do you trust the data / variables

    - by Wizzard
    We all know that all user data, GET/POST/Cookie etc etc needs to be validated for security. But when do you stop, once it's converted into a local variable? eg if (isValidxxx($_GET['foo']) == false) { throw InvalidArgumentException('Please enter a valid foo!'); } $foo = $_GET['foo']; fooProcessor($foo); function fooProcessor($foo) { if (isValidxxx($foo) == false) { throw Invalid...... } //other stuff } To me thats over the top. But what if you load the value from the database... I hope I make sense :)

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