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• How can I implement a splay tree that performs the zig operation last, not first?

  - by Jakob

  For my Algorithms & Data Structures class, I've been tasked with implementing a splay tree in Haskell. My algorithm for the splay operation is as follows: If the node to be splayed is the root, the unaltered tree is returned. If the node to be splayed is one level from the root, a zig operation is performed and the resulting tree is returned. If the node to be splayed is two or more levels from the root, a zig-zig or zig-zag operation is performed on the result of splaying the subtree starting at that node, and the resulting tree is returned. This is valid according to my teacher. However, the Wikipedia description of a splay tree says the zig step "will be done only as the last step in a splay operation" whereas in my algorithm it is the first step in a splay operation. I want to implement a splay tree that performs the zig operation last instead of first, but I'm not sure how it would best be done. It seems to me that such an algorithm would become more complex, seeing as how one needs to find the node to be splayed before it can be determined whether a zig operation should be performed or not. How can I implement this in Haskell (or some other functional language)?

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• Concept: Information Into Memory Location.

  - by Richeve S. Bebedor

  I am having troubles conceptualizing an algorithm to be used to transform any information or data into a specific appropriate and reasonable memory location in any data structure that I will be devising. To give you an idea, I have a JPanel object instance and I created another Container type object instance of any subtype (note this is in Java because I love this language), then I collected those instances into a data structure not specifically just for those instances but also applicable to any type of object. Now my procedure for fetching those data again is to extract the object specific features similar in category to all object in that data structure and transform it into a integer data memory location (specifically as much as possible) or any type of data that will pertain to this transformation. And I can already access that memory location without further sorting or applications of O(n) time complex algorithms (which I think preferable but I wanted to do my own way XD). The data structure is of any type either binary tree, linked list, arrays or sets (and the like XD). What is important is I don't need to have successive comparing and analysis of data just to locate information in big structures. To give you a technical idea, I have to an array DS that contains JLabel object instance with a specific name "HelloWorld". But array DS contains other types of object (in multitude). Now this JLabel object has a location in the array at index [124324] (which is if you do any type of searching algorithm just to arrive at that location is conceivably slow because added to it the data structure used was an array *note please disregard the efficiency of the data structure to be used I just want to explain to you my concept XD). Now I want to equate "HelloWorld" to 124324 by using a conceptually made function applicable to all data types. So that I can do a direct search by doing this DS[extractLocation("HelloWorld")] just to get that JLabel instance. I know this may sound crazy but I want to test my concept of non-sorting feature extracting search algorithm for any data structure wherein my main problem is how to transform information to be stored into memory location of where it was stored.

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• LINQ to SQL - Lightweight O/RM?

  - by CoffeeAddict

  I've heard from some that LINQ to SQL is good for lightweight apps. But then I see LINQ to SQL being used for Stackoverflow, and a bunch of other .coms I know (from interviewing with them). Ok, so is this true? for an e-commerce site that's bringing in millions and you're typically only doing basic CRUDs most the time with the exception of an occasional stored proc for something more complex, is LINQ to SQL complete enough and performance-wise good enough or able to be tweaked enough to run happily on an e-commerce site? I've heard that you just need to tweak performance on the DB side when using LINQ to SQL for a better approach. So there are really 2 questions here: 1) Meaning/scope/definition of a "Lightweight" O/RM solution: What the heck does "lightweight" mean when people say LINQ to SQL is a "lightweight O/RM" and is that true??? If this is so lightweight then why do I see a bunch of huge .coms using it? Is it good enough to run major .coms (obviously it looks like it is) and what determines what the context of "lightweight" is...it's such a generic statement. 2) Performance: I'm working on my own .com and researching different O/RMs. I'm not really looking at the Entity Framework (yet), just want to figure out the LINQ to SQL basics here and determine if it will be efficient enough for me. The problem I think is you can't tweak or control the SQL it generates...

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• Fundamentals of Deserialization in .NET?

  - by Codehelp

  I have been working with XML for past couple of months with .NET Basically all the work I do involve XML in oneway of another so I thought it would be good to learn the serialization and deserialization part of the game. My work mostly involves the 'Deserialization' part of it. Almost every time I have an XML file which has to be used by the application that I write. An object form of the XML is the best way to use. Now initially the XML was very straight forward, just a couple of tags which would translate into a class very easily using XSD.exe tool. Things grew a bit complex with nesting of tags and I found Xsd2Code gen tool work fine. During this whole process I have been able to do my work with a lot of help from Stackoverflow community, thanks for that, but I think I have missed the forest for the trees. I need to know how Deserialization works in .NET Fundamentally, I would like to know what happens behind the scenes in taking a XML and converting it into a usable object. Code samples have helped me in the past, and as mentioned earlier the problem get's solved but the learning does not happen. So, if anyone can guide to resources that can get me started on the Deserialization part of the game, I would be thankful to them. Regards.

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• Is the Subversion 'stack' a realistic alternative to Team Foundation Server?

  - by Robert S.

  I'm evaluating Microsoft Team Foundation Server for my customer, who currently uses Visual SourceSafe and nothing else. They have explicitly expressed a desire to implement a more rigid and process-driven environment as their application is in production and they have future releases to consider. The particular areas I'm trying to cover are: Configuration management (e.g., source control) Change management (workflow and doco for change requests, tasks) Release management (builds and deployments) Incident and problem management (issues and bugs) Document management (similar to source control, but available via web) Code analysis constraints on check-ins A testing framework Reporting Visual Studio 2008 integration TFS does all of these things quite well, but it's expensive and complex to maintain, and the inexpensive Workgroup edition doesn't scale. We don't get TFS as part of our MSDN subscription. Those problems can be overcome, but before I tell my customer to go the TFS route, which in itself isn't a terrible thing, I wanted to evaluate the alternatives. I know Subversion is often suggested for its configuration management/source control, but what about the other areas? Would a combination of Subversion/NUnit/Wiki/CruiseControl/NAnt/something else satisfy all of these requirements? What tools do I need to include in my evaluation? Or should I just bite the bullet and go with TFS since we're already invested in the Microsoft stack?

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• Generating all possible subsets of a given QuerySet in Django

  - by Glen

  This is just an example, but given the following model: class Foo(models.model): bar = models.IntegerField() def __str__(self): return str(self.bar) def __unicode__(self): return str(self.bar) And the following QuerySet object: foobar = Foo.objects.filter(bar__lt=20).distinct() (meaning, a set of unique Foo models with bar <= 20), how can I generate all possible subsets of foobar? Ideally, I'd like to further limit the subsets so that, for each subset x of foobar, the sum of all f.bar in x (where f is a model of type Foo) is between some maximum and minimum value. So, for example, given the following instance of foobar: >> print foobar [<Foo: 5>, <Foo: 10>, <Foo: 15>] And min=5, max=25, I'd like to build an object (preferably a QuerySet, but possibly a list) that looks like this: [[<Foo: 5>], [<Foo: 10>], [<Foo: 15>], [<Foo: 5>, <Foo: 10>], [<Foo: 5>, <Foo: 15>], [<Foo: 10>, <Foo: 15>]] I've experimented with itertools but it doesn't seem particularly well-suited to my needs. I think this could be accomplished with a complex QuerySet but I'm not sure how to start.

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• Asp.net MVC - Model binding image button

  - by big dave

  I've got a very complex form and i'm using the MVC model binding to capture all the information I've got it set up to capture all the different submissions that can happen as there are about 10 different submit buttons on the form, and there are also 2 image buttons I tried to get a bit clever (or so i thought) with capturing the image button submissions, and have created a child class so that i can capture the x value that's returned public class ImageButtonViewData { public int x { get; set; } public string Value { get; set; } } The parent class looks something like this public class ViewDataObject { public ImageButtonViewData ImageButton { get; set; } public ViewDataObject(){ this.ImageButton = new ImageButton(); } } The html for the image button then looks like <input type="image" id="ViewDataObject_ImageButton" name="ViewDataObject.ImageButton" /> This works fine in all browsers except for Chrome. When i debug it in chrome, the Request.Form object contains the values that i would expect, but after the model binding has occurred, the ImageButton property on the ViewDataObject has been set to null The only difference that i can see between the submission values is that Chrome passes the x as lower case (ViewDataObject.ImageButton.x) and IE passes it as upper case (ViewDataObject.ImageButton.X) but i didn't think that model binding took any notice of casing on property names Does anyone have any ideas ?

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• Expanders inside listbox leaving blank space on collapse

  - by siz

  We have a rather complex UI that is presenting some problems for us. I have a ListBox that contains a set of DataItems. The DataTemplate for each item is an Expander. The header is text, the content of the Expander is a ListBox. The ListBox contains SubDataItems. The DataTemplate for each SubDataItem is an Expander. Here is a simplified XAML in which I reproduce the issue: <ListBox ItemsSource="{Binding Items}"> <ListBox.ItemTemplate> <DataTemplate> <Expander Header="{Binding Header}"> <ListBox ItemsSource="{Binding SubItems}"> <ListBox.ItemTemplate> <DataTemplate> <Expander Header="{Binding SubHeader}"> <Grid Height="40"> <TextBlock Text="{Binding SubText}" /> </Grid> </Expander> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Expander> </DataTemplate> </ListBox.ItemTemplate> </ListBox> There is a problem with how the layout is produced. If any Expander corresponding to the SubDataItem is expanded, the ListBoxItem containing this ListBox (the Expander.Content in the parent DataTemplate) correctly requests more space. So I can expand all SubDataItems and correctly see my data. However, when I collapse, the space I previously asked to expand, remains blank, instead of being reclaimed by the ListBoxItem. This is a problem because if I have say 10 SubDataItems and happen to expand all of them at the same time and then collapse, there is a significant amount of white space wasting my real estate. How can I force WPF to resize the ListBoxItem to the correct state?

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• I want to build a Google-friendly web app, where should I start?

  - by ronii

  I have only very basic experience with HTML/CSS and have quite a bit of experience with testing software and web apps from a consumer perspective. I'd love to launch a web application that plays nicely with Google services, similar to some of the apps you'd find on the Google Apps Marketplace, such as ManyMoon, time to note, Socialwok, etc. I'm a huge Google fan and would like to build something that's well integrated with other Google services. If you were a total beginner and wanted to build a complex app like one of examples above (project management, CRM, etc), where would you start? If you worked your ass off 18 hours a day, 24/7, how fast could you do it? I've dabbled into various languages and development frameworks, and read about which apps are using what languages but it's hard to figure out what would be most beneficial to jump into. Ruby on Rails, PHP, Google Web Toolkit, AppEngine. The list goes on and on. I want to be able to build and launch my own scalable web app. Thanks.

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• How do i prevent my code from being stolen?

  - by Calmarius

  What happens exactly when I launch a .NET exe? I know that C# is compiled to IL code and I think the generated exe file just a launcher that starts the runtime and passes the IL code to it. But how? And how complex process is it? IL code is embedded in the exe. I think it can be executed from the memory without writing it to the disk while ordinary exe's are not (ok, yes but it is very complicated). My final aim is extracting the IL code and write my own encrypted launcher to prevent scriptkiddies to open my code in Reflector and just steal all my classes easily. Well I can't prevent reverse engineering completely. If they are able to inspect the memory and catch the moment when I'm passing the pure IL to the runtime then it won't matter if it is a .net exe or not, is it? I know there are several obfuscator tools but I don't want to mess up the IL code itself. EDIT: so it seems it isn't worth trying what I wanted. They will crack it anyway... So I will look for an obfuscation tool. And yes my friends said too that it is enough to rename all symbols to a meaningless name. And reverse engineering won't be so easy after all.

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• Coldfusion 8 and HTTP PUT - is there a way to PUT an object?

  - by ciaranarcher

  Hi all We are using EHCache with CF 8 to cache stuff on a central server using a RESTful interface over HTTP. I am trying to cache a cfquery object to the cache server. I can get this to work if I call EHCache direct (i.e. store it in a local cache) but if I try to cache on a remote server over HTTP I am running into problems. The code I am using is as follows: <cfhttp url="http://localhost:8080/myCache/myKey" method="put" result="r" timeout="2" throwonerror="true" > <cfhttpparam type="body" value="#ARGUMENTS.item#" /> </cfhttp> CF doesn't like this reference to #ARGUMENTS.item# and it complains Complex object types cannot be converted to simple values. Can anyone give me an example of how to put an object over http using CF? If this is not possible with CF then a Java example would be the next best thing. Many thanks in advance! PS: I do not want to use serialization to text/JSON etc. as this approach has issues with data integrity and most importantly it's not fast enough.

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• What's wrong with output parameters?

  - by Chris McCall

  Both in SQL and C#, I've never really liked output parameters. I never passed parameters ByRef in VB6, either. Something about counting on side effects to get something done just bothers me. I know they're a way around not being able to return multiple results from a function, but a rowset in SQL or a complex datatype in C# and VB work just as well, and seem more self-documenting to me. Is there something wrong with my thinking, or are there resources from authoritative sources that back me up? What's your personal take on this and why? What can I say to colleagues that want to design with output parameters that might convince them to use different structures? EDIT: interesting turn- the output parameter I was asking this question about was used in place of a return value. When the return value is "ERROR", the caller is supposed to handle it as an exception. I was doing that but not pleased with the idea. A coworker wasn't informed of the need to handle this condition and as a result, a great deal of money was lost as the procedure failed silently!

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• Stable/repeatable random sort (MySQL, Rails)

  - by Matt Rogish

  I'd like to paginate through a randomly sorted list of ActiveRecord models (rows from MySQL database). However, this randomization needs to persist on a per-session basis, so that other people that visit the website also receive a random, paginate-able list of records. Let's say there are enough entities (tens of thousands) that storing the randomly sorted ID values in either the session or a cookie is too large, so I must temporarily persist it in some other way (MySQL, file, etc.). Initially I thought I could create a function based on the session ID and the page ID (returning the object IDs for that page) however since the object ID values in MySQL are not sequential (there are gaps), that seemed to fall apart as I was poking at it. The nice thing is that it would require no/minimal storage but the downsides are that it is likely pretty complex to implement and probably CPU intensive. My feeling is I should create an intersection table, something like: random_sorts( sort_id, created_at, user_id NULL if guest) random_sort_items( sort_id, item_id, position ) And then simply store the 'sort_id' in the session. Then, I can paginate the random_sorts WHERE sort_id = n ORDER BY position LIMIT... as usual. Of course, I'd have to put some sort of a reaper in there to remove them after some period of inactivity (based on random_sorts.created_at). Unfortunately, I'd have to invalidate the sort as new objects were created (and/or old objects being removed, although deletion is very rare). And, as load increases the size/performance of this table (even properly indexed) drops. It seems like this ought to be a solved problem but I can't find any rails plugins that do this... Any ideas? Thanks!!

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• Is there a case for parameterising using Abstract classes rather than Interfaces?

  - by Chris

  I'm currently developing a component based API that is heavily stateful. The top level components implement around a dozen interfaces each. The stock top-level components therefore sit ontop of a stack of Abstract implementations which in turn contain multiple mixin implementations and implement multiple mixin interfaces. So far, so good (I hope). The problem is that the base functionality is extremely complex to implement (1,000s of lines in 5 layers of base classes) and therefore I do not wish for component writers to implement the interfaces themselves but rather to extend my base classes (where all the boiler plate code is already written). If the API therefore accepts interfaces rather than references to the Abstract implementation that I wish for component writers to extends, then I have a risk that the implementer will not perform the validation that is both required and assumed by other areas of code. Therefore, my question is, is it sometimes valid to paramerise API methods using an abstract implementation reference rather than a reference to the interface(s) that it implements? Do you have an example of a well-designed API that uses this technique or am I trying to talk myself into bad-practice?

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• Design issue when having classes implement different interfaces to restrict client actions

  - by devoured elysium

  Let's say I'm defining a game class that implements two different views: interface IPlayerView { void play(); } interface IDealerView { void deal(); } The view that a game sees when playing the game, and a view that the dealer sees when dealing the game (this is, a player can't make dealer actions and a dealer can't make player actions). The game definition is as following: class Game : IPlayerView, IDealerView { void play() { ... } void deal() { ... } } Now assume I want to make it possible for the players to play the game, but not to deal it. My original idea was that instead of having public Game GetGame() { ... } I'd have something like public IPlayerView GetGame() { ... } But after some tests I realized that if I later try this code, it works: IDealerView dealerView = (IDealerView)GameClass.GetGame(); this works as lets the user act as the dealer. Am I worrying to much? How do you usually deal with this patterns? I could instead make two different classes, maybe a "main" class, the dealer class, that would act as factory of player classes. That way I could control exactly what I would like to pass on the the public. On the other hand, that turns everything a bit more complex than with this original design. Thanks

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• Typical Search, Result and Detail Workflow Staying Within an Android Tab

  - by Justin

  So, I've been banging my head looking for a good solution for a few days and am stuck. I have a search screen (Activity) in a tab, and after the user enters a value and clicks "search" I would like the results to come back in that same tab, and then if an item from the results is selected, to show more detailed results, in that same tab. I have it all working now in separate activities, and even the first step working in a tab, but as soon as I call the activity to process he search results... i.e. startActivity(i); for the results Activity, the results displayed are not in the tab! I am having a very difficult time getting this flow to work all under a tab. Any thoughts on how to make this happen? I keep hearing that Android views should be used instead of activities, but am I then to assume that all the logic I have right now for 3 activity needs to go inside 1 activity and then I need to handle setting the content and state for each of these cases? Plus, won't the history stack not work as pressing the back button will take the user out of the application, instead of taking them from say the search result to the search screen, or the details to the search results, etc. This seems like a mess. Can anyone show a more complex example of tabs or how one might have a simple search, result and detail workflow staying in a tab? I have seen a few questions on this concept of keeping activities "within a tab", but no good resolution. Please help.

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• Unit testing a 'legacy' WPF Application

  - by sc_ray

  The product I have been working on has been in development for the past six years. It started as a generic data entry portal into an insanely complex part WPF/part legacy application. The system has been developed for all these years without a single Unit test in its fold. Now, the point has been raised for a comprehensive unit testing framework. I have been recruited recently to work on this product and have been tasked to get the 'Testing' in order. Since the team that worked on the product for the last six years adopted 'Agile', the project lacks any documentation of the business rules or any design documents. I have been trying to write unit tests for some of the modules. But I am not sure what to Mock, how to setup my Test fixture and eventually what to Test for, since a casual glance of the methods does not reveal its intentions. Also, it has come to my attention that the code was not developed with a particular methodology in mind. Given the situation, I was wondering if the good people of Stackoverflow could provide me with some advise on how to salvage this situation. I have heard about the book 'Working with Legacy Code' that has something to say about this general situation but I was thinking about getting some pointers from individuals who have encountered similar situations within the technology stack(C#,VB,C++,.NET 3.5,WCF,SQL Server 2005).

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• CSS - Positioning images next to text

  - by jpjoki

  Hi, I'm doing a site in which images need to presented next to textual content - a sort of pseudo two-column layout, as the images and text come from a single html source. I've found quite a simple way to do this by putting the images as their own paragraphs and floating them. Would there still be a more simpler way (in regards to html) to do this without these extra paragraphs and by only attributing extra css to images? If the floated image is in the same paragraph than the text, then paragraphs with and without images would be different in width. EDIT: Basically, I'm looking for as simple HTML markup as possible to position images like this. The CSS can be complex ;) CSS: p { width: 500px; } p.image { float: right; width: 900px; } Current HTML: <p class="image"><img src="image.jpg" /></p> <p>Some text here.</p> Is the above possible with this HTML? <p><img src="image.jpg" /></p>

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• c# creating a database query METHOD

  - by Sinaesthetic

  I'm not sure if im delluded but what I would like to do is create a method that will return the results of a query, so that i can reuse the connection code. As i understand it, a query returns an object but how do i pass that object back? I want to send the query into the method as a string argument, and have it return the results so that I can use them. Here's what i have which was a stab in the dark, it obviously doesn't work. This example is me trying to populate a listbox with the results of a query; the sheet name is Employees and the field/column is name. The error i get is "Complex DataBinding accepts as a data source either an IList or an IListSource.". any ideas? public Form1() { InitializeComponent(); openFileDialog1.ShowDialog(); openedFile = openFileDialog1.FileName; lbxEmployeeNames.DataSource = Query("Select [name] FROM [Employees$]"); } public object Query(string sql) { System.Data.OleDb.OleDbConnection MyConnection; System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand(); string connectionPath; //build connection string connectionPath = "provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + openedFile + "';Extended Properties=Excel 8.0;"; MyConnection = new System.Data.OleDb.OleDbConnection(connectionPath); MyConnection.Open(); myCommand.Connection = MyConnection; myCommand.CommandText = sql; return myCommand.ExecuteNonQuery(); }

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• Query crashes MS Access

  - by user284651

  THE TASK: I am in the process of migrating a DB from MS Access to Maximizer. In order to do this I must take 64 tables in MS ACCESS and merge them into one. The output must be in the form of a TAB or CSV file. Which will then be imported into Maximizer. THE PROBLEM: Access is unable to perform a query that is so complex it seems, as it crashes any time I run the query. ALTERNATIVES: I have thought about a few alternatives, and would like to do the least time-consuming one, out of these, while also taking advantage of any opportunities to learn something new. Export each table into CSVs and import into SQLight and then make a query with it to do the same as what ACCESS fails to do (merge 64 tables). Export each table into CSVs and write a script to access each one and merge the CSVs into a single CSV. Somehow connect to the MS ACCESS DB (API), and write a script to pull data from each table and merge them into a CSV file. QUESTION: What do you recommend?

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• MySQL Datefields: duplicate or calculate?

  - by Konerak

  We are using a table with a structure imposed upon us more than 10 years ago. We are allowed to add columns, but urged not to change existing columns. Certain columns are meant to represent dates, but are put in different format. Amongst others: * CHAR(6): YYMMDD * CHAR(6): DDMMYY * CHAR(8): YYYYMMDD * CHAR(8): DDMMYYYY * DATE * DATETIME Since we now would like to do some more complex queries, using advanced date functions, my manager proposed to d*uplicate those problem columns* to a proper FORMATTED_OLDCOLUMNNAME column using a DATE or DATETIME format. Is this the way to go? Couldn't we just use the STR_TO_DATE function each time we accessed the columns? To avoid every query having to copy-paste the function, I could still work with a view or a stored procedure, but duplicating data to avoid recalculation sounds wrong. Solutions I see (I guess I prefer 2.2.1) 1. Physically duplicate columns 1.1 In the same table 1.1.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.1.2 Maintained by a trigger on each modification 1.2 In a separate table 1.2.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.2.2 Maintained by a trigger on each modification 2. On-demand transformation 2.1 Each query has to perform the transformation 2.1.1 Using copy-paste in the source code 2.1.2 Using a library 2.1.3 Using a STORED PROCEDURE 2.2 A view performs the transformation 2.2.1 A separate table replacing the entire table 2.2.2 A separate table just adding the date-fields for the primary keys Am I right to say it's better to recalculate than to store? And would a view be a good solution?

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• Is there a Designer for MFC in Visual Studio like for windows forms in .NET?

  - by claws

  I'm a .NET programmer. I've never developed anything in MFC. Currently I had to write a C++ application (console) for some image processing task. I finished writing it. But the point is I need to design GUI also for this. Well, there won't be anything complex. Just a window with few Buttons, RadioButtons, Check Boxes, PicturesBox & few sliders. thats it. I'm using VS 2008 and was expecting a .NET style form designer. Just to test, I created a MFC project (with all default configuration) and these files were created by default: ChildFrm.cpp MainFrm.cpp mfc.cpp mfcDoc.cpp mfcView.cpp stdafx.cpp Now, I'm unable to find a Designer. There is no View Designer. I've opened all the above *.cpp and in the code editor right clicked to see "Designer View". ToolBox is just empty because I'm in code editor mode. When I built the project. This is the window I get. How to open a designer?

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• 2-column table with two foreign keys. Performance/design question.

  - by Emanuel

  Hello everyone! I recently ran into a quite complex problem and after looking around a lot I couldn't find a solution to it. I've found answers to my questions many times before on stackoverflow.com, so I decided to post here. So I'm making a user/group managment system for a web-based project, and I'm storing all related data into a postgreSQL database. This system relies on three tables: USERS GROUPS GROUP_USERS The two first tables simply define all the users and all the groups on the site, and the last table, GROUP_USERS, stores the groups every user is part of. It only has two columns: USER_ID GROUP_ID Since every user can be a member of several groups, I decided to make a separate table for this purpose, rather than storing a comma separated column in the USERS-table. Now, both columns are foreign keys, and I want to make them both primary keys as well, this since each combination of USER_ID and GROUP_ID has to be unique, and if I give them the constraint UNIQUE pgAdmin tells me that each table should have at least one Primary key. But now I am stuck with what seems to be a lot of indexes and relations to a very small table only containing numbers. In the end, I want this table to be as fast as possible, even if containing tens of thousands of rows. Size on disk shouldn't be a problem since its just all numbers anyway, but it feels quite stupid to have a full-sized index refering to a smaller table. Should I stick with my current solution, store comma-separated values in a column in the USERS-table or is there any other solution I should be aware of. PS. I don't want to use an array-column, even if they are supported by postgreSQL. I want to be as generic as possible so I can switch database later on, if necessary. EDIT: I other words, will using a compound primary key and two foreign keys in one table with only two columns have a negative impact on performance rather than the opposite due to the size of the generated index? Thank you!

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• Are workflows good for web service business logic?

  - by JL

  I have a series of complex web services that are getting used in my SOA application. I am generally happy with the overall design of the application, but as the complexity grows, I was wondering if Windows Workflow might be the way to go. My motivations for this are that you can get a graphic representation of the applications functionality, so it would be easier to maintain the code by its business function, rather than what I have now ( a standard 3 tier class library structure). My concerns are: I would be inducing an abstraction in my code, and I don't want to spend time having to deal with possible WF quirks or bugs. I've never worked with WF, is it a solid technology? I don't want to hit any WF limitations that prevent me from developing my solution. Is a WF even the right solution for the task? Simply put I am considering writing my next web service in this app to call a WF, and in this work flow manage the tasks the web service needs to carry out. I think it will be much neater and easier to maintain than a regular c# class library (maintainable by namespaces, classes ). Do you think this is the right thing to do? I'm hoping for positive feedback on WF (.net 4), but brutal honestly at the end of the day would help more. Thanks

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• Running an application from an USB device...

  - by Workshop Alex

  I'm working on a proof-of-concept application, containing a WCF service with console host and client, both on a single USB device. On the same device I will also have the client application which will connect to this service. The service uses the entity framework to connect to the database, which in this POC will just return a list of names. If it works, it will be used for a larger project. Creating the client and service was easy and this works well from USB. But getting the service to connect to the database isn't. I've found this site, suggesting that I should modify machine.config but that stops the XCopy deployment. This project cannot change any setting of the PC, so this suggestion is bad. I cannot create a deployment setup either. The whole thing just needs to run from USB disk. So, how do I get it to run? (The service just selects a list of names from the database, which it returns to the client. If this POC works, it will do far more complex things!)

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