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  • ASP.NET/VB/SQL: trying to insert data, getting error "no value given for required parameters"

    - by Sara
    I am pretty sure this is a basic syntax error, I am new at this and basically figuring things out by trial and error... I am trying to insert data from textboxes into an Access database, where the primary key fields in tableCourse are prefix and course_number. It keeps giving me the "no value given for one or more required parameters" error. Here is my codebehind: Protected Sub Wizard1_FinishButtonClick(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.WizardNavigationEventArgs) Handles Wizard1.FinishButtonClick 'Collect Data Dim myDept = txtDept.Text Dim myFirst = txtFirstName.Text Dim myLast = txtLastName.Text Dim myPrefix = txtCoursePrefix.Text Dim myNum = txtCourseNum.Text 'Define Connection Dim myConn As New OleDbConnection myConn.ConnectionString = AccessDataSource1.ConnectionString 'Create commands Dim myIns1 As New OleDbCommand("INSERT INTO tableCourse (department, name_first, name_last, prefix, course_number) VALUES (@myDept, @myFirst, @myLast, @myPrefix, @myNum)", myConn) 'Execute the commands myConn.Open() myIns1.ExecuteNonQuery() End Sub

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  • Connection between Properties of Entities in Data Oriented Design

    - by sharethis
    I want to start with an example illustrating my question. The following way it is done in the most games. class car { vec3 position; vec3 rotation; mesh model; imge texture; void move(); // modify position and rotation void draw(); // use model, texture, ... }; vector<car> cars; for(auto i = cars.begin(); i != cars.end(); ++i) { i->move(); i->draw(); } Data oriented design means to process the same calculation on the hole batch of data at once. This way it takes more advantage out of the processor cache. struct movedata { vec3 position; vec3 rotation; }; struct drawdata { mesh model; imge texture; }; vector<movedata> movedatas; vector<drawdata> drawdatas; for(auto i = movedatas.begin(); i != movedatas.end(); ++i) { // modify position and rotation } for(auto i = drawdatas.begin(); i != drawdatas.end(); ++i) { // use model, texture, ... } But there comes a point where you need to find other properties according to an entity. For example if the car crashes, I do not need the drawdata and the movedata any more. So I need to delete the entries of this entity in all vectors. The entries are not linked by code. So my question is the following. How are properties of the same entity conceptually linked in a data oriented design?

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  • How to programaticly access min and Max values defined in a core-data model designed with XCode ?

    - by Xav
    I was expecting to find that in the NSAttributeDescription class, but only the default value is there. Behind the scene I tought a validationPredicate was created but trying to reach it using NSDictionary* dico= [[myManagedObject entity] propertiesByName]; NSAttributeDescription* attributeDescription=[dico objectForKey:attributeKey]; for (NSString* string in [attributeDescription validationWarnings]) just get me nowhere, no validationWarnings, no validationPredicates... any thoughts on this ? Edit1: It seems that getting the entity straight from the managedObject doesn't give you the full picture. Getting the Entity from the NSManagedObjectModel permits to reach the validationWarnings & validationPredicates...

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  • Store data in Ruby on Rails without Database

    - by snowmaninthesun
    I have a few data values that I need to store on my rails app and wanted to know if there are any alternatives to creating a database table just to do this simple task. Background: I'm writing some analytics and dashboard tools for my ruby on rails app and i'm hoping to speed up the dashboard by caching results that will never change. Right now I pull all users for the last 30 days, and re arange them so I can see the number of new users per day. It works great but takes quite a long time, in reality I should only need to calculate the most recent day and just store the rest of the array somewhere else. Where is the best way to store this array? Creating a database table seems a bit overkill, and i'm not sure that global variables are the correct answer. Is there a best practice for persisting data like this? If anyone has done anything like this before let me know what you did and how it turned out.

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  • Help choosing the right data structure

    - by devoured elysium
    I need a data structure with the following requirements: Needs to be able to get elements by index (like a List). I will always just add / remove elements from the end of the structure. I am inclined to use an ArrayList. In this situation, it seems to be O(1) both to read elements (they always are?), remove elements (I only need to remove them at the end of the list) and to add(I only add to the end of the list). There is only the problem that time to time the ArrayList will have a performance penalty when it's completly full and I need to add more elements to it. Is there any other better idea? I don't think of a data structure that'd beat the ArrayList here. Thanks

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  • How to write a value validation method for core data?

    - by mystify
    The docs say: you should implement methods of the form validate:error:, as defined by the NSKeyValueCoding protocol so lets say I have an attribute which is an int: friendAge I want to make sure that any friend may not be younger than 30. So how would I make that validation method? -validateFriendAge:error: What am I gonna do in there, exactly? And what shall I do with that NSError I get passed? I think it has an dictionary where I can return a humanly readable string in an arbitrary language (i.e. the one that's used currently), so I can output a reasonable error like: "Friend is not old enough"... how to do that?

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  • Designing DAOs for data sources other than a database

    - by James P.
    Hi, Until now I've been used to using DAOs to retrieve information from databases. Other sources of data are possible though and I'm wondering if and how the pattern could be applied in general. For example, I'm now working on an application that fetches XML on the web. The XML file could be considered as a data source and the actual fetching is similar in principle to a database request. I'm not quite sure how the DAO could be structured though. Any views on the subject are welcome.

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  • What's does "cardinality of an relationship" mean in Core Data?

    - by dontWatchMyProfile
    From the docs: If all of a managed object's relationship delete rules are Nullify, then for that object at least there is no additional work to do (you may have to consider other objects that were at the destination of the relationship—if the inverse relationship was either mandatory or had a lower limit on cardinality, then the destination object or objects might be in an invalid state). Does someone have an example of this cardinality thing? What's this good for and what's important to know about this? (sounds very important...)

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  • Programming DataEntry&Forms: Population of Official Common Data Lists

    - by rlb.usa
    As a programmer of data-entry forms of all kinds, I often find myself making fields for things like Country and State. Consider: Perhaps a list the 50 United States names is an easy thing to find (does one include DC?) , but the countries are not. Nearly every site you find has a differing list with all of the political goings on over the years, and they become outdated quickly. What's the best practice regarding population of these kinds of lists? Is there an official list somewhere that one uses to populate these kinds of formal/official fields? Where do you get this data from, when it's not exactly specified in the specs?

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  • Which kind of changes can't I do with lightweight migration in Core Data?

    - by dontWatchMyProfile
    I recently tried a lot of different stuff with lightweight migration. These all work: 1) Rename attributes (with renaming identifier specified) 2) Add attributes 3) Add new entity + new attribute + inverse relationship to an already existing entity 4) remove existing entity + relationships to that entity = It almost looks like just about anything can be handled with LM. Did I miss something? In which cases am I getting into trouble and need an some more complex approach?

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  • What happens if a user jumps over 10 versions before updating, and every version had a new data mode

    - by dontWatchMyProfile
    Example: User installs app v.1.0, adds data. Then the dev submits 10 updates in 10 weeks. After 11 weeks, the user wants v.11.0 and grabs a copy from the app store. Assuming that the app has got 11 .xcdatamodel versions inside, where ***11.xcdatamodel is the current one, what would happen now since the persistent store of the user is ages old? would the migration happen 10 times, step-by-step through every migration iteration? Or does the actual migration of data (lets assume gigabytes of data) happen exactly once, after Core Data (or the persistent store coordinator) has figured out precisely what to do to go from v.1.0 to v.11.0?

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  • Most performant way to check how many objects are referenced by an to-many relationship in Core Data

    - by dontWatchMyProfile
    Lets say I have an employees relationship in an Company entity, and it's to-many. And they're really many. Apple in 100 years, with 1.258.500.073 employees. Could I simply do something like NSInteger numEmployees = [apple.employees count]; without firing 1.258.500.073 faults? (Well, in 100 years, the iPhone will easily handle so many objects, for sure...but anyways)

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  • Entity Framework 4 & WCF Data Service: N:M mapping

    - by JJO
    I have three tables in my database: An A table, a B table, and a many-to-many ABMapping table. For simplicity, A and B are keyed with identity columns; ABMapping has just two columns: AId and BId. I built an Entity Framework 4 model from this, and it did correctly identify the N:M mapping between A and B. I then built a WCF Data Service based on this EF model. I'm trying to consume this WCF Data Service. Unfortunately, I can't figure out how to get a mapping between As and Bs to map back to the database. I've tried something like this: A a = new A(); B b = new B(); a.Bs.Add(b); connection.SaveChanges(); But this doesn't seem to have worked. Any clues? What am I missing?

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  • Twin edges - Half edge data structure

    - by Pradeep Kumar
    I have implemented a Half-edge data structure for loading 3d objects. I find that the part of assigning twin/pair edges takes the longest computation time (especially for objects which have hundreds of thousands half edges). The reason is that I use nested loops to accomplish this. Is there a simpler and efficient way of doing this? Below is the code which I've written. HE is the half-edge data structure. hearr is a vector containing all the half edges. vert is the starting vertex and end is the ending vertex. Thanks!! HE *e1,*e2; for(size_t i=0;i<hearr.size();i++){ e1=hearr[i]; for(size_t j=1;j<hearr.size();j++){ e2=hearr[j]; if((e1->vert==e2->end)&&(e2->vert==e1->end)){ e1->twin=e2; e2->twin=e1; } } }

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  • NSPredicate (Core Data fetch) to filter on an attribute value being present in a supplied set (list)

    - by starbaseweb
    I'm trying to create a fetch predicate that is the analog to the SQL "IN" statement, and the syntax to do so with NSPredicate escapes me. Here's what I have so far (the relevant excerpt from my fetching routine): NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease]; NSEntityDescription *entity = [NSEntityDescription entityForName: @"BodyPartCategory" inManagedObjectContext:_context]; [request setEntity:entity]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(name IN %@)", [RPBodyPartCategory defaultBodyPartCategoryNames]]; [request setPredicate:predicate]; The entity "BodyPartCategory" has a string attribute "name". I have a list of names (just NSString objects) in an NSArray as returned by: [RPBodyPartCategory defaultBodyPartCategoryNames] So let's say that array has string such as {@"Liver", @"Kidney", @"Thyroid"} ... etc. I want to fetch all 'BodyPartCategory' instances whose name attribute matches one of the strings in the set provided (technically NSArray but I can make it an NSSet). In SQL, this would be something like: SELECT * FROM BodyPartCategories WHERE name IN ('Liver', 'Kidney', 'Thyroid') I've gone through various portions of the Predicate Programming Guide, but I don't see this simple use case covered. Pointers/help much appreciated!

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  • Core Animation cross-dissolve between one string (or image) and another when changing bound value?

    - by danwood
    I have an NSTextView and an NSImageView that is bound to a NSString and an NSImage in my code. I would like to have the displayed string and image cross-dissolve when I change the string and image in code. Any way to do this? Do I need to stop using bindings? (And if I do, is there any trick to getting the string and the image to cross-dissolve when I change the value, or do I have to do something weird like fade it out and fade a new one back in?)

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  • Where does one get data like Country:(list) State:(list)

    - by rlb.usa
    As a programmer of data-entry forms of all kinds, I often find myself making fields for things like Country: <choose from list>, State: <choose from list>, Race/Ethnicity: <choose from list>. Consider: Perhaps a list the 50 United States names is an easy thing to find (does one include DC?) , but the countries are not. Nearly every site you find has a differing list with all of the political goings on over the years, and they become outdated quickly. What's the best/common practice regarding population of these kinds of lists? Where does this data come from if it's not given in the specs?

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  • The data structure of libev watchers

    - by changchang
    Libev uses three data structures to storage different watchers. Heap: for watchers that sorted by time, such as ev_timer and ev_periodic. Linked list: such as ev_io, ev_signal, ev_child and etc. Array: such as ev_prepare, ev_check, ev_async and etc. There is no doubt about that uses heap to store timer watcher. But what is the criteria of selecting linked list and array? The data structure that stores ev_io watchers seems a little complex. It first is an array that with fd as its index and the element in the array is a linked list of ev_io watcher. It is more convenient to allocate space for array if use linked list as element. Is it the reason? Or just because of the insert or remove operation of ev_io is more frequently and the ev_prepare seems more stable? Or any other reasons?

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