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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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  • NHibernate: Many-to-many relationship with field in the relationship table

    - by Fossmo
    I'm scratching my head; I have a Car table and a Customer table that have a many-to-many relationship. In this relationship table I want to add a column that can tell me what kind of relationship this is; is the customer testdriving the car, do he want to buy the car, ect. What I want to end up with is a class Car object that holds a collection of Customers and the relationship information. I might be looking at this the wrong way so feel free to push me in the right direction.

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  • Core data many-to-many relationship - Predicate question

    - by Garry
    In my Core Data model I have two entities: List and Patient. List has an attribute called 'name'. A List can have any number of Patients and each Patient can belong to any number of different lists. I have therefore set a relationship on List called 'patients' that has an inverse to-many relationship to Patient AND a relationship on Patient called 'lists' that has a to-many relationship to List. What I'm struggling to figure out is how to create a Predicate that will select all Patients that belong to a particular List name. How would I go about this? I have never used relationships before in Core Data. Thanks,

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  • SQLAlchemy - relationship limited on more than just the foreign key

    - by Marian
    I have a wiki db layout with Page and Revisions. Each Revision has a page_id referencing the Page, a page relationship to the referenced page; each Page has a all_revisions relationship to all its revisions. So far so common. But I want to implement different epochs for the pages: If a page was deleted and is recreated, the new revisions have a new epoch. To help find the correct revisions, each page has a current_epoch field. Now I want to provide a revisions relation on the page that only contains its revisions, but only those where the epochs match. This is what I've tried: revisions = relationship('Revision', primaryjoin = and_( 'Page.id == Revision.page_id', 'Page.current_epoch == Revision.epoch', ), foreign_keys=['Page.id', 'Page.current_epoch'] ) Full code (you may run that as it is) However this always raises ArgumentError: Could not determine relationship direction for primaryjoin condition ...`, I've tried all I had come to mind, it didn't work. What am I doing wrong? Is this a bad approach for doing this, how could it be done other than with a relationship?

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  • Core Data migration of to-one relationship to to-many relationship

    - by westsider
    I have a deployed app that samples measurements from sensors (e.g., Temp °C, Pressure kPa). The user can create Experiments and collect samples. Each sample is stored as a Run, such that there is a one-to-many relationship from Experiment to Run. In the interest of performance, Run has a to-one relationship with Data entity (which is where the actual raw data is stored); this allows some Run attributes to be loaded without necessarily loading lots of data. Most of our sensors have multiple measurements, so it would be nice to store all the data that is actually being sampled. But this means that the Run <--- Data relationship needs to become Run <-- Data (to use Xcode's convention). I am faced with trying to migrate data from old Run to-one Data model to new Run to-many Data model. Can this be done using Mapping Models? If so, does anyone have any pointers to examples? If not, does anyone have any pointers to examples of how to do that? Thanks for any pointers or advice.

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  • Laravel 4 showing all field from one to one relationship in

    - by rivai04
    I'm trying to show all field of the chosen row from one to one relationship... Route Route::get('relasi-pasien', function() { $pasien = PasienIri::where('no_ipd', '=', '100')->first(); foreach($pasien->keadaanumum as $temp) { echo'<li> Name : '.$temp->name. 'Tekdar: '.$temp->tekdar. 'Nadi : '.$temp->nadi. '</li>'; } }); Relation at PasienIri's model public function keadaanumum() { return $this->hasOne('KeadaanUmum', 'no_ipd'); } Relation at KeadaanUmum's Model public function pasieniri() { return $this->belongsTo('PasienIri', 'no_ipd'); } When I used that way, it showed error: 'Trying to get property of non-object' But if I just trying to show only one of the field, it works, showing one field: Route::get('relasi-pasien', function() { $pasien = PasienIri::where('no_ipd', '=', '100')->first(); return $pasien->keadaanumum->name; }); anyone could help me to show all field with one to one relationship or I really have to change it to one to many relationship? cause if I change it to one to many relationship, it works

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  • MYSQL in PHPMYADMIN - create table relationship from one table

    - by Stanley DecoWood
    I want to create a table relationship with MYSQL PHPMYADMIN. I have this Create table: CREATE TABLE students(code_students int(8)not null AUTO_INCREMENT, name_students varchar(25), age_students int(3), degree_program varchar(25), code_advisor int(8)not null, primary key(code_students, code_advisor) ); and i want to make a create table named advise relationship between code_students, code_advisor.

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  • Decoding relationship between two numbers?

    - by Nimbuz
    Is there any way (or calculator) to determine the relationship between two numbers. For example on one the temporary event ID cards, the Unique ID is 20309825 but the barcode when decoded reads 8336902052. What could be the relationship between these numbers, if any? Thanks in advance for your help!

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  • Core data relationship memory leak

    - by cfihelp
    I have a strange (to me) memory leak when accessing an entity in a relationship. Series and Tiles have an inverse relationship to each other. // set up the fetch request NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Series" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // grab all of the series in the core data store NSError *error = nil; availableSeries = [[NSArray alloc] initWithArray:[managedObjectContext executeFetchRequest:fetchRequest error:&error]]; [fetchRequest release]; // grab one of the series Series *currentSeries = [availableSeries objectAtIndex:1]; // load all of the tiles attached to the series through the relationship NSArray *myTiles = [currentSeries.tile allObjects]; // 16 byte leak here! Instruments reports back that the final line has a 16 byte leak cause by NSPlaceHolderString. Stack trace: 2 UIKit UIApplicationMain 3 UIKit -[UIApplication _run] 4 CoreFoundation CFRunLoopRunInMode 5 CoreFoundation CFRunLoopRunSpecific 6 GraphicsServices PurpleEventCallback 7 UIKit _UIApplicationHandleEvent 8 UIKit -[UIApplication sendEvent:] 9 UIKit -[UIApplication handleEvent:withNewEvent:] 10 UIKit -[UIApplication _runWithURL:sourceBundleID:] 11 UIKit -[UIApplication _performInitializationWithURL:sourceBundleID:] 12 Memory -[AppDelegate_Phone application:didFinishLaunchingWithOptions:] /Users/cfish/svnrepo/Memory/src/Memory/iPhone/AppDelegate_Phone.m:49 13 UIKit -[UIViewController view] 14 Memory -[HomeScreenController_Phone viewDidLoad] /Users/cfish/svnrepo/Memory/src/Memory/iPhone/HomeScreenController_Phone.m:58 15 CoreData -[_NSFaultingMutableSet allObjects] 16 CoreData -[_NSFaultingMutableSet willRead] 17 CoreData -[NSFaultHandler retainedFulfillAggregateFaultForObject:andRelationship:withContext:] 18 CoreData -[NSSQLCore retainedRelationshipDataWithSourceID:forRelationship:withContext:] 19 CoreData -[NSSQLCore newFetchedPKsForSourceID:andRelationship:] 20 CoreData -[NSSQLCore rawSQLTextForToManyFaultStatement:stripBindVariables:swapEKPK:] 21 Foundation +[NSString stringWithFormat:] 22 Foundation -[NSPlaceholderString initWithFormat:locale:arguments:] 23 CoreFoundation _CFStringCreateWithFormatAndArgumentsAux 24 CoreFoundation _CFStringAppendFormatAndArgumentsAux 25 Foundation _NSDescriptionWithLocaleFunc 26 CoreFoundation -[NSObject respondsToSelector:] 27 libobjc.A.dylib class_respondsToSelector 28 libobjc.A.dylib lookUpMethod 29 libobjc.A.dylib _cache_addForwardEntry 30 libobjc.A.dylib _malloc_internal I think I'm missing something obvious but I can't quite figure out what. Thanks for your help! Update: I've copied the offending chunk of code to the first part of applicationDidFinishLaunching and it still leaks. Could there be something wrong with my model?

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  • ruby on rails one-to-many relationship

    - by fenec
    I would like to model a betting system relationship using the power of rails. so lets start with doing something very simple modelling the relationship from a user to a bet.i would like to have a model bet with 2 primary keys. here are my migrations enter code here class CreateBets < ActiveRecord::Migration def self.up create_table :bets do |t| t.integer :user_1_id t.integer :user_2_id t.integer :amount t.timestamps end end def self.down drop_table :bets end end class CreateUsers < ActiveRecord::Migration def self.up create_table :users do |t| t.string :name t.timestamps end end def self.down drop_table :users end end the models enter code here class Bet < ActiveRecord::Base belongs_to :user_1,:class_name=:User belongs_to :user_2,:class_name=:User end class User < ActiveRecord::Base has_many :bets, :foreign_key =:user_1) has_many :bets, :foreign_key =:user_2) end when i test here in the console my relationships I got an error enter code here u1=User.create :name="aa" = # u2=User.create :name="bb" = # b=Bet.create(:user_1=u1,:user_2=u2) *****error***** QUESTIONS: 1 How do I define the relationships between these tables correctly? 2 are there any conventions to name the attributes (ex:user_1_id...) thank you for your help

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  • NSManagedObject relationship undo

    - by Reflog
    I have a NSManagedObject ObjA that has a many-to-many relationship with another NSManagedObject ObjB. I initialize it with [NSEntityDescription insertNewObjectForEntityForName:@"ObjA" inManagedObjectContext:app.context]; When I perform undo without performing save - the object is not added to the persistent store. But - when I add an item to the collection inside ObjA and then perform undo - the ObjA is not added, but ObjB is not, it's still lingering in the persisten store for some reason. Any ideas what am I doing wrong?

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  • Oracle Unveils Oracle Social Relationship Management Suite at Oracle OpenWorld

    - by Richard Lefebvre
    New Service Enables Companies to Listen, Engage, Create, Market and Analyze Interactions across Multiple Social Platforms in Real-Time During his keynote presentation, Oracle CEO Larry Ellison announced the Oracle Social Relationship Management (SRM) Suite.   Oracle Social Relationship Management Suite is an integrated enterprise service that enables companies to listen, engage, create, market, and analyze interactions across multiple social platforms in real-time providing a holistic view of the consumer.   Oracle Social Relationship Management Suite is integrated with Oracle’s enterprise applications, including Oracle Fusion Marketing, Oracle Fusion Sales Catalog, Oracle ATG Web Commerce, and Oracle Enterprise Resource Planning (ERP), allowing organizations to use social to transform their corporate business processes and systems.   Additionally, Oracle Social Relationship Management Suite is integrated with Oracle Platform Services, including Oracle Java Cloud Service and Oracle Database Cloud Service, enabling marketing teams to integrate social with their custom Web pages, landing pages and marketing tools. Unleashing the Power of Social • Providing a holistic view of consumer interactions, Oracle Social Relationship Management Suite includes: Oracle Social Network (OSN): Provides a secure collaboration platform that supports real-time collaboration and networking for users inside and outside the organization. Oracle Social Marketing: Enables marketers to centrally create, publish, moderate, manage, measure and report across multiple social campaigns and platforms. It also helps marketers publish social content, engage fans and customize their brand's look and feel. Oracle Social Engagement & Monitoring Cloud Service: Enables organizations to analyze social media interactions while also empowering customer service and sales teams to effectively engage with customers and prospects. It gives organizations the tools they need to understand customers and take the appropriate actions by monitoring, listening, learning, and responding to signals and trends across the social web. Oracle Social Sites: provides brands and agencies a powerful and rich editing experience that end users can leverage to dynamically develop and launch social sites. Oracle Data and Insights. A service that caters to a growing enterprise need for externally information by providing information, directory and insights about common business entities. Supporting Quote “By fundamentally changing the way organizations connect with their different stakeholders, social is changing the rules of business,” said Thomas Kurian, executive vice president, Oracle Product Development. “With the Oracle Social Relationship Management Suite we are empowering our customers to embrace this change by integrating the tools required to listen, engage, create, market and analyze social interactions into existing applications and services.”

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  • Accessing the relationship of a relationship with Entity Framework

    - by J. Pablo Fernández
    I the School class I have this code: from student in this.Students where student.Teacher.Id == id select student The Student class there are two relationships: Teacher and School. In the School class I'm trying to find out all the students whose Teacher has a given id. The problem is that I get System.NullReferenceException: Object reference not set to an instance of an object. in the statement student.Teacher.Id I thought of doing this.Students.Include("Teacher"), but this.Students doesn't have such a method. Any ideas how can I perform that query?

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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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  • sharepoint list relationship question

    - by Korey
    I have two custom lists in sharepoint with a one to many relationship on a column in both lists. So list A has text column 1 and list B has a lookup column 1' on list A's column 1. I want to display the rows in list A, where column 1 has a match on column 1' and a 2nd column in list B with a specific text string. I have Sharepoint Designer and am fumbling along with linked sources described here http://office.microsoft.com/en-us/sharepointdesigner/HA100991441033.aspx, but can't get exactly what I'm looking for.

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  • Core Data - Relationship to dissimilar entities

    - by carotene
    Suppose I have the following data model: Entity Person Attribute name String Attribute personType String Attribute dailyRecords Entity CarpenterDailyRecord Attribute numberOfNailsHammered Int Attribute picNameOfFinishedCabinet String Entity WindowWasherDailyRecord Attribute nameOfBuildingWashed String Attribute numberOfWindowsWashed Int I would like to establish a to-many relationship between the Person.dailyRecords and 1 of the daily record entities (which changes depending on the person type). Of course, i could create a CarpenterPerson and WindowWasher entity which each points to it's unique daily record structure, but i have to group people together in my app somehow. so if i do a Group Entity: Entity Group Attribute people array i'm still stuck. how do i point to multiple & different Person entities? There must be an obvious answer, it's just i'm so new to all of this. thanks!

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  • Rails has_and_belongs_to_many relationship question

    - by Kevin Whitaker
    Hello all, I'm sure that this question has been asked somewhere before, as the habtm relationship seems to be very confusing. I have two models, users and promotions. The idea is that a promotion can have many users, and a user can have many promotions. class User < ActiveRecord::Base has_and_belongs_to_many :promotions end class Promotion < ActiveRecord::Base has_and_belongs_to_many :users end I also have a promotions_users table/model, with no id of its own. It references user_id and promotions_id class PromotionsUsers < ActiveRecord::Base end So, how do I add a user to a promotion? I've tried something like this: user = User.find(params[:id]) promotion = Promotion.find(params[:promo_id]) promo = user.promotions.new(promo) This results in the following error: NoMethodError: undefined method `stringify_keys!' for #<Promotion:0x10514d420> If I try this line instead: promo= user.promotions.new(promo.id) I get this error: TypeError: can't dup Fixnum I'm sure that there is a very easy solution to my problem, and I'm just not searching for the solution the right way. Thank you for your time, and any help you can provide.

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  • GAE modeling relationship options

    - by Sway
    Hi there, I need to model the following situation and I can't seem to find a consistent example on how to do it "correctly" for the google app engine. Suppose I've got a simple situation like the following: [Company] 1 ----- M [Stare] A company has one to many stores. Each store has an address made up of a address line 1, city, state, country, postcode etc. Ok. Lets say we need to create say an "Audit". An Audit is for a company and can be across one to many stares. So something like: [Audit] 1 ------ 1 [Company] 1 ------ M [Store] Now we need to query all of the "audits" based on the Store "addresses" in order to send the "Auditors" to the right locations. There seem to be numerous articles like this one: http://code.google.com/appengine/articles/modeling.html Which give examples of creating a "ContactCompany" model class. However they also say that you should use this kind of relationship only when you "really need to" and with "care" for performance. I've also read - frequently - that you should denormalize as much as possible thereby moving all of the "query-able" data into the Audit class. So what would you suggest as the best way to solve this? I've seen that there is an Expando class but I'm not sure if that is the "best" option for this. Any help or thoughts on this would be totally appreciated. Thanks in advance, Matt

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  • General many-to-many relationship problem ( Postgresql )

    - by David
    Hi, i have two tables: CREATE TABLE "public"."auctions" ( "id" VARCHAR(255) NOT NULL, "auction_value_key" VARCHAR(255) NOT NULL, "ctime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, "mtime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, CONSTRAINT "pk_XXXX2" PRIMARY KEY("id"), ); and CREATE TABLE "public"."auction_values" ( "id" NUMERIC DEFAULT nextval('default_seq'::regclass) NOT NULL, "fk_auction_value_key" VARCHAR(255) NOT NULL, "key" VARCHAR(255) NOT NULL, "value" TEXT, "ctime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, "mtime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, CONSTRAINT "pk_XXXX1" PRIMARY KEY("id"), ); if i want to create a many-to-many relationship on the auction_value_key like this: ALTER TABLE "public"."auction_values" ADD CONSTRAINT "auction_values_fk" FOREIGN KEY ("fk_auction_value_key") REFERENCES "public"."auctions"("auction_value_key") ON DELETE NO ACTION ON UPDATE NO ACTION NOT DEFERRABLE; i get this SQL error: ERROR: there is no unique constraint matching given keys for referenced table "auctions" Question: As you might see, i want "auction_values" to be be "reused" by different auctions without duplicating them for every auction... So i don't want a key relation on the "id" field in the auctions table... Am i thinking wrong here or what is the deal? ;) Thanks

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  • In Visio 2010, how can I create a mandatory, non-identifying relationship between two database tables

    - by Cam Jackson
    I'm working in MS Visio 2010. This is the relevant part of my ERD: The relationship between Event and Adventure is correct: there's a foreign key from Event to Adventure, and that FK is part of Event's primary key. However, what I can't figure out is how to make the relationship line from Adventure to AccomodationType be the same, without making that relationship part of the PK of adventure. When I look at the 'Miscellaneous' properties of that relationship line, I want it to be: Cardinality: Zero or more Relationship type: Non-identifying Child has parent: Not optional (mandatory) But the checkbox for the third property is greyed out, and toggles between True/False as I make the relationship Non-identifying/Identifying. The only way I could figure out was to disconnect the two columns, from the 'Definition' tab, which then un-grey's the 'Optional' checkbox, but then I lose the foreign key property on the accomType column, and while the relationship symbols are correct, the line remains dotted. Any ideas, anyone?

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