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• Entity Relationship Model: Ternary Relationships

  - by Ethan

  Hi, I am trying to understand why this statement in the book is wrong: "given a C entity, there is at most one related A entity and at most one related B entity". Is it that it doesn't apply to a specific kind of relationship?? So, if I have an example of a student who is in attendance to a course with a type of subject. The entities are student, attendance, course and subject. Student makes attendance in a room. Also, a student can make attendance for a subject. Does this example apply to the statement? Thanks for your time.

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• Which layer should create DataContext?

  - by Kevin

  I have a problem to decide which layer in my system should create DataContext. I have read a book, saying that if do not pass the same DataContext object for all the database updates, it will sometimes get an exception thrown from the DataContext. That's why i initially create new instance of DataContext in business layer, and pass it into data access layer. So that the same datacontext is used for all the updates. But this lead to one design problem, if i wanna change my DAL to Non-LinqToSQL in future, i need to re-write the code in business layer as well. Please give me some advice on this. Thanks. Example code 'Business Layer Public Sub SaveData(name As String) Using ts AS New TransactionScope() Using db As New MyDataContext() DAL.Insert(db,name) DAL.Insert(db,name) End Using ts.Complete() End Using End Sub 'Data Access Layer Public Sub Insert(db as MyDataContext,name As string) db.TableAInsert(name) End Sub

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• MCTS exam 70-526 vs 70-505

  - by doug.stanhope

  I guess this should be CW but I don't know how to post a question as such, so if anyone can help out... What I would like to know is the following: I have taken exam 70-526 a couple of years ago and I still have the training kit laying around. Now my boss wants me to prepare for the upgrade exam 70-505. Do you know if both exams are similar or otherwise put: do you think I have to get the new training kit to prepare for this exam or will the old one do? I haven't done a whole lot of Windows Forms programming these past few years so I'll have to re-learn much of what's in the book.

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• myth about factory pattern

  - by leiz

  This has bothered me for awhile, and I have no clues if this is a myth. It seems that a factory pattern can ease the pain of adding a dependency for a class. For example, in a book, it has something like this Suppose that you have a class named Order. Initially it did not depend on anything. Therefore you didn't bother using a factory to create Order objects and you just used plain new to instantiate the objects. However, you now have a requirement that Order has to be created in association with a Customer. There are million places you need to change to add this extra parameter. If only you had de?ned a factory for the Order class, you would have met the new requirement without the same pain. How is this not same pain as adding an extra parameter to the constructor? I mean you would still need to provide an extra argument for the factory and that is also used by million places, right?

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• Python: Filter a dictionary

  - by Adam Matan

  Hi, I have a dictionary of points, say: >>> points={'a':(3,4), 'b':(1,2), 'c':(5,5), 'd':(3,3)} I want to create a new dictionary with all the points whose x and y value is smaller than 5, i.e. points 'a', 'b' and 'd'. According to the the book, each dictionary has the items() function, which returns a list of (key, pair) tuple: >>> points.items() [('a', (3, 4)), ('c', (5, 5)), ('b', (1, 2)), ('d', (3, 3))] So I have written this: >>> for item in [i for i in points.items() if i[1][0]<5 and i[1][1]<5]: ... points_small[item[0]]=item[1] ... >>> points_small {'a': (3, 4), 'b': (1, 2), 'd': (3, 3)} Is there a more elegant way? I was expecting Python to have some super-awesome dictionary.filter(f) function... Adam

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• Real time web services

  - by daliz

  Hi everybody, I have a little (maybe the answer could require a book) question about web services and server side programming. But first, a little preamble. Recently we have seen new kind of applications & games using some kind of real-time interaction with a database, or more generally, with other users. I'm talking about shared drawing canvas, games like this , or simple chats, or the Android app "a World of Photo", where in real time you see who is online, to share your photos, etc. Now my question: Are all these apps based on classic TCP client/server architectures or is there a way to make them in a simpler way, like a web platform like LAMP? What I'm asking, in other words is: Can PHP+MySQL (or JSP, or RoR, or any other server language) provide a way to make online users communicate in real time and share data? Is there a way to do that without the ugly and heavy mechanism of temporary tables? Thank you! I hope I've been clear.

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• Continuing education with Visual Basic 9

  - by TSSH

  I am completely new to programming and starting my education with visual basic 9 and SQL. I have read Visual Basic, in easy steps, 2nd edition by Mike Mcgrath. Although it was very easy to understand, it only gave me an introduction to learning VB. I'm looking for something more in depth, albeit for a beginner. I've read through the questions with a VB and book tag. Unfortunately, most of what I've found here references VB 6 and VB 8. Any recommendations? I cannot afford to create a library or college at the moment. So, I need to make sure that what I do buy counts. Thanks for any suggestions!

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• Whats the significance of named scope in rails?

  - by piemesons

  Before going for details. Question 1:-- Whats the meaning of scope here (ie named scope)? whats the benefits of using named scope? Now:- from agile development with rails book:-- class Order < ActiveRecord::Base named_scope :last_n_days, lambda { |days| {:conditions => ['updated < ?' , days] } } named_scope :checks, :conditions => {:pay_type => :check} end Such a named scope would make finding the last weeks worth of orders a snap. orders = Orders.last_n_days(7) Scopes can also be combined orders = Orders.checks.last_n_days(7) why we are using named_scope here. We can do the same using methods. Whats special thing we got using named_scope.

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• Lexical and dynamic scoping in Mathematica: Local variables with Module, With, and Block

  - by dreeves

  The following code returns 14 as you'd expect: Block[{expr}, expr = 2 z; f[z_] = expr; f[7]] But if you change that Block to a Module then it returns 2*z. It seems to not matter what other variables besides expr you localize. I thought I understood Module, Block, and With in Mathematica but I can't explain the difference in behavior between Module and Block in this example. Related resources: Tutorial on Modularity and the Naming of Things from the Mathematica documentation Excerpt from a book by Paul R. Wellin, Richard J. Gaylord, and Samuel N. Kamin Explanation from Dave Withoff on the Mathematica newsgroup

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• How to prepare for a Java test?

  - by Zenzen

  Ok so in two days I have a test for my dream job (well it's an internship, but still!) and for quite some time now I've been reading the SCJP Guide book in order to prepare myself. BUT seeing how slow my reading speed is I guess finding a website with some "java essentials" or "standard java test questions" and going through it in those 2 days would be a better idea. Don't misunderstand me, I do have java experience and it's "only" an internship, but we all know how programming tests look like and how tricky they can be. So are there any online resources you could recommend me? I know 2 days is not much, but well I was informed bout the test 1-2days ago.

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• OOP Design Question - Where/When do you Validate properties?

  - by JW

  I have read a few books on OOP DDD/PoEAA/Gang of Four and none of them seem to cover the topic of validation - it seems to be always assumed that data is valid. I gather from the answers to this post (http://stackoverflow.com/questions/1651964/oop-design-question-validating-properties) that a client should only attempt to set a valid property value on a domain object. This person has asked a similar question that remains unanswered: http://bytes.com/topic/php/answers/789086-php-oop-setters-getters-data-validation#post3136182 So how do you ensure it is valid? Do you have a 'validator method' alongside every getter and setter? isValidName() setName() getName() I seem to be missing some key basic knowledge about OOP data validation - can you point me to a book that covers this topic in detail? - ie. covering different types of validation / invariants/ handling feedback / to use Exceptions or not etc

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• cakePHP - ACL tutorial & SQL Error: 1104

  - by vector

  Greetings! I run into a problem/bug in production environment with SQL Error: 1104 when deploying a project secured with the ACL tutorial. The full error: SQL Error: 1104: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET SQL_MAX_JOIN_SIZE=# if the SELECT is okay [CORE/cake/libs/model/datasources/dbo_source.php, line 666] I've build a small site, worked through the ACL tutorial from the official cake book and locally everything is spiffy. dev. setup consists of: XAMPP: myslq 5.1.33, php 5.3 cakePHP 1.2.7 prod. setup: mysql 5.0.33 php 5.2.2 One of the differences I noticed with mysql setup between local and production servers, is that SQL_BIG_SELECTS is disabled on the production server ( and I don't have privileges to change that, posted a support ticked, didn't hear anything yet) Is there anything I can do about this from my end? Thanks in advance.

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• asp.net mvc 2: SportsStore application: The current request for action is ambiguous

  - by dotnet-practitioner

  I am working on SportsStore example on chapter 4 from the following book and getting stuck... Pro Asp.net mvc framework I get the following error: The current request for action 'List' on controller type 'ProductsController' is ambiguous between the following action methods: System.Web.Mvc.ViewResult List() on type WebUI.Controllers.ProductsController System.Web.Mvc.ViewResult List(Int32) on type WebUI.Controllers.ProductsController .. My router code looks as follows: public static void RegisterRoutes(RouteCollection routes) { routes.MapRoute( null, // Route name "", // URL with parameters new { controller = "Products", action = "List", page=1 } ); routes.MapRoute( null, // Route name "Page{page}", // URL with parameters new { controller = "Products", action = "List" }, // Parameter defaults new { page = @"\d+" } ); } and controller code looks as follows: public ViewResult List() { return View(productsRepository.Products.ToList()); } public ViewResult List(int page) { return View(productsRepository.Products .Skip((page - 1) * PageSize) .Take(PageSize) .ToList()); } What am I missing? my url is as follows: http://localhost:1103/ or http://localhost:1103/Page1 or http://localhost:1103/Page2 thanks

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• Outlook VBA to BCC emails sent not working in outlook 2007

  - by Pixfizz

  Inserted code in "ItemSend" and saved the ThisOutlookSession module. It worked once and no longer works. Before anyone asks; it was saved as BVaproject.OTM and is still there when I open the module back up after restarting outlook. Private Sub Application_ItemSend(ByVal Item As Object, _ Cancel As Boolean) Dim objRecip As Recipient Dim strMsg As String Dim res As Integer Dim strBcc As String On Error Resume Next ' #### USER OPTIONS #### ' address for Bcc -- must be SMTP address or resolvable ' to a name in the address book strBcc = "[email protected]" Set objRecip = Item.Recipients.Add(strBcc) objRecip.Type = olBCC If Not objRecip.Resolve Then strMsg = "Could not resolve the Bcc recipient. " & _ "Do you want still to send the message?" res = MsgBox(strMsg, vbYesNo + vbDefaultButton1, _ "Could Not Resolve Bcc Recipient") If res = vbNo Then Cancel = True End If End If Set objRecip = Nothing End Sub

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• what architecture for implementing a richtext editor?

  - by genesys

  Hi! Can someone give me some hints on how a clean implementation (designwise) of a richtext editor could look like that allows for things like setting fonts, setting character colors and so on? And when and how are characters rendered? are characters rendered only once and the bitmap representation is cached? Is there any article or book covering what software design would be appropriate for that? background is that we're working on a text editing software for a language that cannot be displayed with unicode any hint is appreciated! thanks!

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• Why am I getting unexpected output trying to write a hash structure to a file?

  - by Harm De Weirdt

  I have a hash in which I store the products a customer buys (%orders). It uses the product code as key and has a reference to an array with the other info as value. At the end of the program, I have to rewrite the inventory to the updated version (i.e. subtract the quantity of the bought items) This is how I do rewrite the inventory: sub rewriteInventory{ open(FILE,'>inv.txt'); foreach $key(%inventory){ print FILE "$key\|$inventory{$key}[0]\|$inventory{$key}[1]\|$inventory{$key}[2]\n" } close(FILE); } where $inventory{$key}[x] is 0 → Title, 1 → price, 2 → quantity. The problem here is that when I look at inv.txt afterwards, I see things like this: CD-911|Lady Gaga - The Fame|15.99|21 ARRAY(0x145030c)||| BOOK-1453|The Da Vinci Code - Dan Brown|14.75|12 ARRAY(0x145bee4)||| Where do these ARRAY(0x145030c)||| entries come from? Or more important, how do I get rid of them?

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• struct function

  - by gcc

  typedef struct phoneEntry { struct phoneEntry* next; char* info; char* number; } phoneEntry; typedef struct contactEntry { struct contactEntry* next; char* name; char* surname; struct phoneEntry* phoneList; } contactEntry; I want write a function that add a new contact to the phone book using given name and surname.(please, Note that a new contact should be located in the proper location which ensures the alphabetical ordering of the contacts.) void addContact(contactEntry** phoneBook, char* name, char* surname) { } I tried to write ,but ,unfortunetely, I cannot question is that there are any person who can help me.

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• Is there any need to get a Computer Science degree?

  - by Tom Moseley

  I've been a software developer for 20 years. i've been involved in language development and large data warehouse development. I've worked for start-ups that have gone public, and for government contractors, and I've written a published programming book. My knowledge is either self-taught or on-the-job. I've worked with some of the best and brightest, and they taught me well. I'm back in school now, and am weighing my options, deciding between a Computer Science and a business degree. My question is this. What do I gain, at this point in my career, by earning a Computer Science degree? I just don't know if a Computer Science degree, at this point, is a value-add on my resume. Edit: I'm working on completing an undergraduate degree.

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• What are the Worst Software Project Failures Ever?

  - by Warren P

  Is there a good list of "worst software project failures ever" in the history of software development? For example in Canada a "gun registry" project spent around two billion dollars. (http://en.wikipedia.org/wiki/Gun_registry). This is of course, insane, even if the final product "sort of worked". I have heard of an FBI Case file system which there have been several attempts to rewrite, all of them so far, failures. There is a book on the subject (Software Runaways). There doesn't seem to be be a software "boondoggle" list or "fiasco" list on Wikipedia that I can see. (Update: Therac-25 would be the 'winner' of this question, except that I was internally thinking more of Software projects that had as their deliverable, mainly software, as opposed to firmware projects like Therac-25, where the hardware and firmware together are capable of killing people. In terms of pure software monetary debacles, which was my intended question, there are several contenders.)

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• iPhone facebook connect FQL Query to get Profile URL.

  - by user306641

  Hai. I am using Face book Connect FQL Queries to extract my profile photo url that is src_big,src_small URL. But i am always getting the empty array in below delegate (void)request:(FBRequest*)request didLoad:(id)result My FQL query is. NSString* fql = [NSString stringWithFormat:@"SELECT src_big,src_small FROM photo WHERE pid IN (SELECT cover_pid FROM album WHERE owner =%lld AND name ='Profile Pictures')", session.uid]; NSDictionary* params = [NSDictionary dictionaryWithObject:fql forKey:@"query"]; [[FBRequest requestWithDelegate:self] call:@"facebook.fql.query" params:params]; But - (void)request:(FBRequest*)request didLoad:(id)result always return the empty result. Can any one please correct me if there any mistake.

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• Web Crawling Sites with Javascripts or web forms

  - by Jojo

  Hello everyone, I have a webcrawler application. It successfully crawled most common and simple sites. Now i ran into some types of websites wherein HTML documents are dynamically generated through FORMS or javascripts. I believe they can be crawled and I just don't know how. Now, these websites do not show the actual HTML page. I mean if I browse that page in IE or firefox, the HTML code does not match what's actually in the IE or firefox. These sites contain textboxes, checkboxes, etc... so I believe they are what they call "Web Forms". Actually I am not much familiar with web development so correct me if I'm wrong. My question is, does anyone in similar situation as I am now and have successfully solved these types of "challenges"? Does anyone know of a certain book or article regarding web crawling? Those that pertains to these advanced type of websites? Thanks.

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• Help with parsing lxml

  - by Casey

  Hi To implement a college project, I need to handle XML files. For this I choose lxml after doing some research. However I can't seem to find some nice tutorial to help me get started. I can't choose most specifically which type of parsing I need to use. My XML files don't have that much data but speed is main concern, not memory. Can anyone point me to some tutorial that would help me or some book that I can lookup? I have already tried the tutorial on lxml site but that didn't help me much. Is there some small application I can look up to get a hang of parsing XML with lxml

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• Using XPath to access comments a flat hierachy

  - by Sebastian

  I have a given XML document (structure can not be changed) and want to get the comments that are written above the nodes. The document looks like this: <!--Some comment here--> <attribute name="Title">Book A</attribute> <attribute name="Author"> <value>Joe Doe</value> <value>John Miller</value> </attribute> <!--Some comment here--> <attribute name="Code">1</attribute> So comments are optional, but if there is one, I want to get the comment above each attribute. Using /*/comment()[n] would give me comment n, but for n=2 I would naturally get the comment of the third attribute, so there is no connection between attributes and comments Any ideas? Thanks

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• ASP.NET-MVC2 Preview 1: Are There Any Breaking Changes?

  - by Jim G.

  I was following Steven Sanderson's 'Pro ASP.NET MVC Framework' book. On page 132, in accordance with the author's recommendation, I downloaded the ASP.NET MVC Futures assembly, and added it to my MVC project. Then, without encouragement from the author, I downloaded, installed, and incorporated the ASP.NET MVC2 Preview 1 dlls into my project. Now, I can no longer load the website. That is, when I hit F5 in Visual Studio, I get this error. In retrospect, I think it was a really bad idea to assume that ASP.NET MVC2 Preview 1 would only be additive; but I'd like other people to weigh in. Has anyone noticed any breaking changes in ASP.NET MVC 2 Preview 1? Also - Has anyone noticed any changes that impact Castle Windsor? Also, please let me know if I should be mindful of IIS6 vs. IIS7 ramifications.

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• [as3] list cellRenderer

  - by lemon

  I'm quite new with as3 via cs4 so please bear with me. I'm trying to make a phone book type list that displays the users name, cellnumber and possible a delete button. --- Bob 09XXXXXXXXX delete --- Sussie 09XXXXXXXXX delete --- Johnny 09XXXXXXXXX delete --- I've tried making a list and added to it a XML dataprovider <profiles> <profile> <label>Bob</label> ... </profile> It'll then display a list of names Bob Sussie Johnny But what do I have to do in order to get it print like fig 1? I know that it has something to do with CellRender but I can't seem to find any decent examples in Google.

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