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  • How to update correctly an Entity Model after changes of database structure?

    - by Slauma
    I've made some changes in the table structure and especially the relationships between tables in my SQL Server database. Now I want to update my Entity model based on this new database structure. Right clicking on the edmx file I find the option "Update model from database". But when I do this I get kind of a 50% update: The new columns appear in the Entity classes but I am confused about a lot of navigation properties which are still there in the model although the corresponding foreign key relationships do not exist anymore in the database. Am I doing something wrong? Or is there another option to update the model including deletion of navigation properties? Or do I have to delete those navigation properties manually in the model files? I am using Entity Framework Version 1 (VS 2008 SP1). Thanks for help in advance!

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  • MS SQL Bridge Table Constraints

    - by greg
    Greetings - I have a table of Articles and a table of Categories. An Article can be used in many Categories, so I have created a table of ArticleCategories like this: BridgeID int (PK) ArticleID int CategoryID int Now, I want to create constraints/relationships such that the ArticleID-CategoryID combinations are unique AND that the IDs must exist in the respective primary key tables (Articles and Categories). I have tried using both VS2008 Server Explorer and Enterprise Manager (SQL-2005) to create the FK relationships, but the results always prevent Duplicate ArticleIDs in the bridge table, even though the CategoryID is different. I am pretty sure I am doing something obviously wrong, but I appear to have a mental block at this point. Can anyone tell me please how should this be done? Greaty appreciated!

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  • Entity Relationship Diagram - Relationship Strength?

    - by 01010011
    Hi, I am trying to figure out under what circumstances I should use weak (non-identifying) relationships (where the primary key of the related entity does not contain a primary key component of the parent entity), verses when I should use strong (identifying) relationships (primary key of the related entity contains a primary key component of the parent entity). For example, when designing an Entity Relationship Diagram , if I have two entities, (e.g. book and purchaser), how do I know when to choose the solid Crows Foot or the dashed Crows Foot to connect the two entities? Any assistance will be appreciated. Thanks in advance.

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  • Database structure - To join or not to join

    - by Industrial
    Hi! We're drawing up the database structure with the help of mySQL Workbench for a new app and the number of joins required to make a listing of the data is increasing drastically as the many-to-many relationships increases. The application will be quite read-heavy and have a couple of hundred thousand rows per table. The questions: Is it really that bad to merge tables where needed and thereby reducing joins? Should we start looking at horizontal partitioning? (in conjunction with merging tables) Is there a better way then pivot tables to take care of many-to-many relationships? We discussed about instead storing all data in serialized text columns and having the application make the sorting instead of the database, but this seems like a very bad idea, even though that the database will be heavily cached. What do you think? Thanks!

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  • Is it worthwhile to implement observer pattern in PHP?

    - by Extrakun
    I have been meaning to make use of design pattern in PHP, such as the observer pattern, but that I have to recreate the observers' relationship each time the page is loaded pains me. As references are saved as a new concrete objects in session, there is no way to preserve relationships between subscribers and their observers unless you use a GUID or some other properties to form a lookup, and store that property instead. With the cost of recreating the relationships each time a page is loaded, is it worthwhile to use design patterns such as observers in PHP, compared to having a clean design? Any real-world experience to share?

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  • Adding unique objects to Core Data

    - by absolut
    I'm working on an iPhone app that gets a number of objects from a database. I'd like to store these using Core Data, but I'm having problems with my relationships. A Detail contains any number of POIs (points of interest). When I fetch a set of POI's from the server, they contain a detail ID. In order to associate the POI with the Detail (by ID), my process is as follows: Query the ManagedObjectContext for the detailID. If that detail exists, add the poi to it. If it doesn't, create the detail (it has other properties that will be populated lazily). The problem with this is performance. Performing constant queries to Core Data is slow, to the point where adding a list of 150 POI's takes a minute thanks to the multiple relationships involved. In my old model, before Core Data (various NSDictionary cache objects) this process was super fast (look up a key in a dictionary, then create it if it doesn't exist) I have more relationships than just this one, but pretty much every one has to do this check (some are many to many, and they have a real problem). Does anyone have any suggestions for how I can help this? I could perform fewer queries (by searching for a number of different ID's), but I'm not sure how much this will help. Some code: POI *poi = [NSEntityDescription insertNewObjectForEntityForName:@"POI" inManagedObjectContext:[(AppDelegate*)[UIApplication sharedApplication].delegate managedObjectContext]]; poi.POIid = [attributeDict objectForKey:kAttributeID]; poi.detailId = [attributeDict objectForKey:kAttributeDetailID]; Detail *detail = [self findDetailForID:poi.POIid]; if(detail == nil) { detail = [NSEntityDescription insertNewObjectForEntityForName:@"Detail" inManagedObjectContext:[(AppDelegate*)[UIApplication sharedApplication].delegate managedObjectContext]]; detail.title = poi.POIid; detail.subtitle = @""; detail.detailType = [attributeDict objectForKey:kAttributeType]; } -(Detail*)findDetailForID:(NSString*)detailID { NSManagedObjectContext *moc = [[UIApplication sharedApplication].delegate managedObjectContext]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Detail" inManagedObjectContext:moc]; NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease]; [request setEntity:entityDescription]; NSPredicate *predicate = [NSPredicate predicateWithFormat: @"detailid == %@", detailID]; [request setPredicate:predicate]; NSLog(@"%@", [predicate description]); NSError *error; NSArray *array = [moc executeFetchRequest:request error:&error]; if (array == nil || [array count] != 1) { // Deal with error... return nil; } return [array objectAtIndex:0]; }

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  • Database Instance

    - by Sam
    I read a statement from an exercise: construct a database instance which conforms to diagram 1 but not to diagram 2. The diagrams are different n-ary relationships that have different relationships. Diagram 1 has a many to one to many to one relationship. Diagram 2 has many to many to many to one relationship. So, to really understand this problem, what does a database instance mean? Is it to make an example or abstract entities like a1, a2, or a3. Thanks for your time.

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  • Is there a Drupal module for Forms with powerful CRUD style behaviour?

    - by Petras
    We are building a website that contains a large number of database tables that need to be edited by the CMS administrator. Some of the tables are fed by form submissions from users on the front end of the website. Some of the tables are purely in the CMS and are used to create custom modules on the front end of the website. Although there is a forms module in Drupal, I think our requirements cannot be met by it. Does anyone know of a system that allows forms to be saved to a CRUD style database with the following features? Export of all database fields. View a summary of the records in a filterable table. With paging You can have one to many relationships in records eg To code this manually for 10 forms is A LOT of work. Particularly the one to many relationships. If there is a powerful module available it would save us writing one.

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  • Sqlalchemy+elixir: How query with a ManyToMany relationship?

    - by Hugo
    Hi, I'm using sqlalchemy with Elixir and have some troubles trying to make a query.. I have 2 entities, Customer and CustomerList, with a many to many relationship. customer_lists_customers_table = Table('customer_lists_customers', metadata, Column('id', Integer, primary_key=True), Column('customer_list_id', Integer, ForeignKey("customer_lists.id")), Column('customer_id', Integer, ForeignKey("customers.id"))) class Customer(Entity): [...] customer_lists = ManyToMany('CustomerList', table=customer_lists_customers_table) class CustomerList(Entity): [...] customers = ManyToMany('Customer', table=customer_lists_customers_table) I'm tryng to find CustomerList with some customer: customer = [...] CustomerList.query.filter_by(customers.contains(customer)).all() But I get the error: NameError: global name 'customers' is not defined customers seems to be unrelated to the entity fields, there's an special query form to work with relationships (or ManyToMany relationships)? Thanks

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  • Database designing for a bug tracking system in SQL

    - by Yasser
    I am an ASP.NET developer and I really dont do such of database stuff. But for my open source project on Codeplex I am required to setup a database schema for the project. So reading from here and there I have managed to do the following. As being new to database schema designing, I wanted some one else who has a better idea on this topic to help me identify any issues with this design. Most of the relationships are self explanatory I think, but still I will jot each one down. The two keys between UserProfile and Issues are for relationships between UserId and IssueCreatedBy and IssueClosedBy Thanks

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  • Using Multiple Foreign Keys to the same table in LINQ

    - by Graeme
    I have a table Users and a table Items In the Items table, I have fields such as ModifiedBy CreatedBy AssignedTo which all have a userId integer. The database is set up to have these as foreign keys back to the Users table. When using LINQToSQL, the relationships which are automatically built from the dbml end up giving me names like User, User1 and User2 e.g. myItem.User1.Name or myItem.User2.Name Obviously this isn't very readable and I'd like it be along the lines of myItem.CreatedByUser.Name or myItem.ModifiedByUser.Name etc I could change the names of the relationships but that means I have to redo that every time I change the db schema and refresh the dbml. Is there any way round this?

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  • Entity Framework: Data Centric vs. Object Centric

    - by Eric J.
    I'm having a look at Entity Framework and everything I'm reading takes a data centric approach to explaining EF. By that I mean that the fundamental relationships of the system are first defined in the database and objects are generated that reflect those relationships. Examples Quickstart (Entity Framework) Using Entity Framework entities as business objects? The EF documentation implies that it's not necessary to start from the database layer, e.g. Developers can work with a consistent application object model that can be mapped to various storage schemas When designing a new system (simplified version), I tend to first create a class model, then generate business objects from the model, code business layer stuff that can't be generated, and then worry about persistence (or rather work with a DBA and let him worry about the most efficient persistence strategy). That object centric approach is well supported by ORM technologies such as (n)Hibernate. Is there a reasonable path to an object centric approach with EF? Will I be swimming upstream going that route? Any good starting points?

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  • Kohana 3 ORM limitations

    - by yoda
    Hi, What are the limitations of Kohana 3 ORM regarding table relationships? I'm trying to modify the build-in Auth module in order to accept groups of users in adition, having now the following tables : groups groups_users roles roles_groups users user_tokens By default, this module is set to work without groups, and linking the users and roles using a third table named roles_users, but I need to add groups to it. I'm linking, as you can see by the names, the groups to users and the roles to groups, but I'm failing building the ORM code for it, so that's pretty much the question here, if ORM is limited to 2 relationships or if it can handle 3 in this case. Cheers!

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  • jQuery Cycle Plugin - Content not cycling

    - by fmz
    I am setting up a page with jQuery's Cycle plugin and have four divs set to fade. I have the code in place, the images set, but it doesn't cycle properly. Firefox says there is a problem with the following code: <script type="text/javascript"> $(document).ready(function() { $('.slideshow').cycle({ fx: 'fade' }); }); </script> Here is the html: <div class="slideshow"> <div id="mainImg-1" class="slide"> <div class="quote"> <h2>Building Big Relationships with Small Business.</h2> <p>&ldquo;This is quote Number One.<br /> They are there when I need them the most.&rdquo;</p> <p><span class="author">Jane Doe &ndash; Charlotte Flower Shop</span></p> <div class="help"><a href="cb_services.html">Let Us Help You</a></div> </div> </div> <div id="mainImg-2" class="slide"> <div class="quote"> <h2>Building Big Relationships with Small Business.</h2> <p>&ldquo;This is quote Number Two.<br /> They are there when I need them the most.&rdquo;</p> <p><span class="author">Jane Doe &ndash; Charlotte Flower Shop</span></p> <div class="help"><a href="cb_services.html">Let Us Help You</a></div> </div> </div> <div id="mainImg-3" class="slide"> <div class="quote"> <h2>Building Big Relationships with Small Business.</h2> <p>&ldquo;This is quote Number three.<br /> They are there when I need them the most.&rdquo;</p> <p><span class="author">Jane Doe &ndash; Charlotte Flower Shop</span></p> <div class="help"><a href="cb_services.html">Let Us Help You</a></div> </div> </div> <div id="mainImg-4" class="slide"> <div class="quote"> <h2>Building Big Relationships with Small Business.</h2> <p>&ldquo;This is quote Number Fout.<br /> They are there when I need them the most.&rdquo;</p> <p><span class="author">Jane Doe &ndash; Charlotte Flower Shop</span></p> <div class="help"><a href="cb_services.html">Let Us Help You</a></div> </div> </div> Here is the CSS: .slideshow { width: 946px; height: 283px; border: 1px solid #c29c5d; margin: 8px; overflow: hidden; z-index: 1; } #mainImg-1 { width: 946px; height: 283px; background: url(../_images/main.jpg) no-repeat 9px 9px; } #mainImg-2 { width: 946px; height: 283px; background: url(../_images/main.jpg) no-repeat 9px 9px; } #mainImg-3 { width: 946px; height: 283px; background: url(../_images/main.jpg) no-repeat 9px 9px; } #mainImg-4 { width: 946px; height: 283px; background: url(../_images/main.jpg) no-repeat 9px 9px; } #mainImg-1 .quote, #mainImg-2 .quote, #mainImg-3 .quote, #mainImg-4 .quote { width: 608px; height: 168px; float: right; margin: 80px 11px 0 0; background: url(../_images/bg_quoteBox.png) repeat-x; } Before you go off and say, "hey, those images are all the same". You are right, the images are all the same right now, but the text should be rotating as well and there is a slight difference there. In addition, the fade should still show up. Anyway, you can see the dev page here: http://173.201.163.213/projectpath/first_trust/index.html I would appreciate some help to get this cycling through as it should. Thanks!

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  • Implementing tagging in JDO

    - by Julie Paltrow
    I am implementing a tagging system for a website that uses JDO . I would like to use this method. However I am new to relationships in JDO. To keep it simple, what I have looks like this: @PersistentCapable class Post { @Persistent String title; @Persistent String body; } @PersistentCapable class Tag { @Persistent String name; } What kind of JDO relationships do I need and how to implement them? I want to be able to list all Tags that belong to a Post, and also be able to list all Posts that have a given Tag. So in the end I would like to have something like this: Table: Post Columns: PostID, Title, Body Table: Tag Columns: TagID, name Table: PostTag Columns: PostID, TagID

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  • How do I update with a newly-created detached entity using NHibernate?

    - by Daniel T.
    Explanation: Let's say I have an object graph that's nested several levels deep and each entity has a bi-directional relationship with each other. A -> B -> C -> D -> E Or in other words, A has a collection of B and B has a reference back to A, and B has a collection of C and C has a reference back to B, etc... Now let's say I want to edit some data for an instance ofC. In Winforms, I would use something like this: var instanceOfC; using (var session = SessionFactory.OpenSession()) { // get the instance of C with Id = 3 instanceOfC = session.Linq<C>().Where(x => x.Id == 3); } SendToUIAndLetUserUpdateData(instanceOfC); using (var session = SessionFactory.OpenSession()) { // re-attach the detached entity and update it session.Update(instanceOfC); } In plain English, we grab a persistent instance out of the database, detach it, give it to the UI layer for editing, then re-attach it and save it back to the database. Problem: This works fine for Winform applications because we're using the same entity all throughout, the only difference being that it goes from persistent to detached to persistent again. The problem occurs when I'm using a web service and a browser, sending over JSON data. In this case, the data that comes back is no longer a detached entity, but rather a transient one that just happens to have the same ID as the persistent one. If I use this entity to update, it will wipe out the relationship to B and D unless I sent the entire object graph over to the UI and got it back in one piece. Question: My question is, how do I serialize detached entities over the web, receive them back, and save them, while preserving any relationships that I didn't explicitly change? I know about ISession.SaveOrUpdateCopy and ISession.Merge() (they seem to do the same thing?), but this will still wipe out the relationships if I don't explicitly set them. I could copy the fields from the transient entity to the persistent entity one by one, but this doesn't work too well when it comes to relationships and I'd have to handle version comparisons manually.

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  • cant use Activerecord find method with associations.

    - by fenec
    here are my models: #game class Game < ActiveRecord::Base #relationships with the teams for a given game belongs_to :team_1,:class_name=>"Team",:foreign_key=>"team_1_id" belongs_to :team_2,:class_name=>"Team",:foreign_key=>"team_2_id" def self.find_games(name) items = Game.find(:all,:include=>[:team_1,:team_2] , :conditions => ["team_1.name = ?", name] ) end end #teams class Team < ActiveRecord::Base #relationships with games has_many :games, :foreign_key =>'team_1' has_many :games, :foreign_key =>'team_2' end When i execute Game.find_games("real") i get : ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: team_1.name How can i fix the problem i thought that using :include would fix the problem.

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  • To join or not to join - database structure

    - by Industrial
    Hi! We're drawing up the database structure with the help of mySQL Workbench for a new app and the number of joins required to make a listing of the data is increasing drastically as the many-to-many relationships increases. The questions: Is it really that bad to merge tables where needed and thereby reducing joins? Is there a better way then pivot tables to take care of many-to-many relationships? We discussed about instead storing all data in serialized text columns and having the application make the sorting instead of the database, but this seems like a very bad idea, even though that the database will be heavily cached. What do you think? Thanks!

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  • TSQL, select values from large many-to-many relationship

    - by eugeneK
    I have two tables Publishers and Campaigns, both have similar many-to-many relationships with Countries,Regions,Languages and Categories. more info Publisher2Categories has publisherID and categoryID which are foreign keys to publisherID in Publishers and categoryID in Categories which are identity columns. On other side i have Campaigns2Categories with campaignID and categoryID columns which are foreign keys to campaignID in Campaigns and categoryID in Categories which again are identities. Same goes for Regions, Languages and Countries relationships I pass to query certain publisherID and want to get campaignIDs of Campaigns that have at least one equal to Publisher value from regions, countries, language or categories thanks

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  • Doctrine: Relating a model to itself using a link table, like "This event is related to to the following other events"

    - by mattalexx
    So in English, the relationship would sound like "This event is related to to the following other events". My first instinct is to create an EventEvent model, with a first_event_id field and a second_event_id field. Then I would define the following two relationships in the Event model: $this->hasMany('Event as FirstRelatedEvents', array('local' => 'first_event_id', 'foreign' => 'second_event_id', 'refClass' => 'EventEvent')); $this->hasMany('Event as SecondRelatedEvents', array('local' => 'second_event_id', 'foreign' => 'first_event_id', 'refClass' => 'EventEvent')); But I would rather not have to use two relationships on the Event model. Is there a better way to do this?

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  • Ria Services loading foreign keys with Linq-to-SQL

    - by Stephan
    I have a database that consists of 5 tables : Course, Category, Location, CourseCategories, and CourseLocations. The last 2 tables just contain the two foreign keys. A Course has many-to-many relationships with both category and location. I am trying to load the data into a Silverlight app using Ria Services. My DB model is Linq-to-SQL. I have tried adding the [Include] attribute to the metadata classes and I have added the DataLoadOptions so it should load the all tables when you ask for a Course. However on the client side I am never getting back any entries in the CourseCategories and CourseLocations properties. What else needs to be done to get the foreign key relationships to exist across the serialization.

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  • What is the difference between causal models and directed graphical models?

    - by Neil G
    What is the difference between causal models and directed graphical models? or: What is the difference between causal relationships and directed probabilistic relationships? or, even better: What would you put in the interface of a DirectedProbabilisticModel class, and what in a CausalModel class? Would one inherit from the other? Collaborative solution: interface DirectedModel { map<Node, double> InferredProbabilities(map<Node, double> observed_probabilities, set<Node> nodes_of_interest) } interface CausalModel: DirectedModel { bool NodesDependent(set<Node> nodes, map<Node, double> context) map<Node, double> InferredProbabilities(map<Node, double> observed_probabilities, map<Node, double> externally_forced_probabilities, set<Node> nodes_of_interest) }

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  • Correct association mapping in Entity Framework

    - by Matt Thrower
    Hi, Trying to change two relationships in our entity framework from many-to-one to many-to-many relationships. So I tried the obvious thing: clicked on each association on the diagram, changed the appropriate end of the association accordingly and then changed the name of the navigation property to a plural to reflect the change. This lead to the following build error, or one each for the two changes I've made: Error 3002: Problem in mapping fragments starting at line 1761:Potential runtime violation of table CustomerServices's keys (CustomerServices.Id): Columns (CustomerServices.Id) are mapped to EntitySet CompiledDatabaseCustomerService's properties (CompiledDatabaseCustomerService.CustomerService.Id) on the conceptual side but they do not form the EntitySet's key properties (CompiledDatabaseCustomerService.CompiledDatabase.Id, CompiledDatabaseCustomerService.CustomerService.Id) I'm not entirely sure why this is happening, so unsurprisngly I haven't had much luck fixing it. I've tried fiddling with the mapping details and adding referential constraints to no avail. Anyone point me in the right direction? cheers, Matt

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  • SQL Analysis Services - Dimension attributes with a "many" cardinality

    - by MonkeyBrother
    I am creating a cube with the following tables: Customer CustomerID, Name Customer Rep CustomerID, RepID Rep RepID, Name The important thing here is that there is a many to many relationship between Reps and Customers. I want to be able to ask the question "How much sales for customers working with rep 'A'?" In the data source view i set up the relationships between both customerid columns and both repid columns. I set up the rep attribute in the dimension builder and when I try to build the cube I get this error: Errors in the high-level relationship engine. the 'Rep' table that is required for a join cannot be reached based on the relationships in the data source view.

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  • What to do if 2 (or more) relationship tables would have the same name?

    - by primehunter326
    So I know the convention for naming M-M relationship tables in SQL is to have something like so: For tables User and Data the relationship table would be called UserData User_Data or something similar (from here) What happens then if you need to have multiple relationships between User and Data, representing each in its own table? I have a site I'm working on where I have two primary items and multiple independent M-M relationships between them. I know I could just use a single relationship table and have a field which determines the relationship type, but I'm not sure whether this is a good solution. Assuming I don't go that route, what naming convention should I follow to work around my original problem?

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