Search Results

Search found 1115 results on 45 pages for 'relationships'.

Page 28/45 | < Previous Page | 24 25 26 27 28 29 30 31 32 33 34 35  | Next Page >

• Please suggest me the best way to design my database.

  - by Raymond Ho

  I have a table named "Pages" and a table named "Categories". Each entry of the table "Pages" is linked to the table "Categories". The "Categories" table have 5 entries, they are: "Car", "Websites", "Technology", "Mobile Phones", and "Interest". So each time I put an entry to the "Pages" table, I need to map it to the "Categories" table so are arranged properly. Here's my table: Pages ______ id [PK] name url Categories ______ id [PK] Categoryname Pages2Categories ______ Pages.id Categories.id So my question is, is this the most efficient way to create this kind of relationships between tables? It seems very amateur

  Read the article

• Resources for learning how to better read code

  - by rsteckly

  Hi, I recently inherited a large codebase and am having to read it. The thing is, I've usually been the dev starting a project. As a result, I don't have a lot of experience reading code. My reaction to having to read a lot of code is, well, umm to rewrite it. But I need to bring myself up to speed quickly and build on top of an existing system. Do other people have techniques they've learned to absorb a code base? At this point, I'm just reading through the code. I've tried generating UML diagrams using UModel. They're so big they won't print cleanly and when I zoom in, I really do lose the perspective of seeing all the relationships. How have other people dealt with this problem?

  Read the article

• SQL Server (2008) Creating link tables with unique rows

  - by peteski22

  Hi guys, I'm having trouble getting in touch with SQL Server Managemen Studio 2008! I want to create a link-table that will link an Event to many Audiences (EventAudience). An example of the data that could be contained: EventId | AudienceId 4 1 5 1 4 2 However, I don't want this: EventId | AudienceId 4 1 4 1 I've been looking at relationships and constraints.. but no joy so far! As a sneaky second part to the question, I would like to set up the Audience table such that if a row is deleted from Audience, it will clear down the EventAudience link table in a cascading manner. As always, ANY help/advice appreciated! Thanks Pete

  Read the article

• jpa join query on a subclass

  - by Brian

  I have the following relationships in JPA (hibernate). Object X has two subclasses, Y and Z. Object A has a manyToOne relationship to object X. (Note, this is a one-sided relationship so object X cannot see object A). Now, I want to get the max value of a column in object A, but only where the relationship is of a specific subtype, ie...Y. So, that equates to...get the max value of column1 in object A, across all instances of A where they have a relationship with Y. Is this possible? I'm a bit lost as how to query it. I was thinking of something like: String query = "SELECT MAX(a.columnName) FROM A a join a.x; Query query = super.entityManager.createQuery(query); query.execute(); However that doesn't take account of the subclass of X...so I'm a bit lost. Any help would be much appreciated.

  Read the article

• A general question about compilation and interpretation.

  - by wucnuc

  Hi stackoverflow, I apologize in advance for the possible stupidity of this question. However, the following has been the source of some confusion for me and I know the people here will be able to handily clear up the confusion for me. Basically, I would like to finally understand the relationship between any and all of the following terms. Some of the terms I do actually understand pretty well, but some of them are similar in my mind and I would like to once and for all to see their relationships/distinctions laid out all at once. They are: compiler interpreter bytecode machine code assembler assembly language binary object code executable Ideally, an answer would use examples from Java and C++ and other well-known programming languages that a young-ish student like me would be familiar with. Also, if you want to throw in any other useful terms that would be fine too :)

  Read the article

• How To Query Many-to-Many Table (one table's values becomes column headers)

  - by CRice

  Given this table structure, I want to flatten out the many-to-many relationships and make the values in the Name field of one table into column headers and the quantities from the same table into column values. The current idea which will work is to put the values into a Dictionary (hashtable) and represent this data in code but im wondering if there is a SQL way to do this. I am also using Linq-to-SQL for data access so a Linq-to-SQL solution would be ideal. [TableA] (int Id) [TableB] (int id, string Name) [TableAB] (int tableAId, int tableBId, int Quantity) fk: TableA.Id joins to TableAB.tableAId fk: TableB.Id joins to TableAB.tableBId Is there a way I can query the three tables and return one result for example: TableA [Id] 1 TableB [Id], [Name] 1, "Red" 2, "Green" 3, "Blue" TableAB [TableAId], [TableBId], [Quantity] 1 1 5 1 2 6 1 3 7 Query Result: [TableA.Id], [Red], [Green], [Blue] 1, 5, 6, 7

  Read the article

• Microsoft Access - Enter Parameter Value why?

  - by Jane Doe

  I am encountering a problem for my database. Here is the relationships of the database And tried to do the query for how many transactions have movie "Harry_Potter"? so I used SQL query: SELECT COUNT(td.movie) AS number_of_occurrence, td.transaction_number FROM TransactionDetails td, MovieDetails md WHERE md.movie = Harry_Potter But it asks for Harry_Potter enter parameter value why? The relevant SQL statements are CREATE TABLE TransactionDetails ( transaction_number INTEGER PRIMARY KEY, movie VARCHAR(30) NOT NULL, date_of_transaction DATE NOT NULL, member_number INTEGER NOT NULL ) CREATE TABLE MovieDetails ( movie VARCHAR(30) PRIMARY KEY, movie_type VARCHAR(3) NOT NULL, movie_genre VARCHAR(10) NOT NULL ) ALTER TABLE TransactionDetails ADD CONSTRAINT member_number_fk FOREIGN KEY (member_number) REFERENCES LimelightMemberDetails(member_number); ALTER TABLE TransactionDetails ADD CONSTRAINT transaction_number_drink_fk FOREIGN KEY (transaction_number) REFERENCES DrinkTransactionDetails(transaction_number); ALTER TABLE TransactionDetails ADD CONSTRAINT transaction_number_food_fk FOREIGN KEY (transaction_number) REFERENCES FoodTransactionDetails(transaction_number); ALTER TABLE TransactionDetails ADD CONSTRAINT movie_fk FOREIGN KEY (movie) REFERENCES MovieDetails (movie); Thank you for your help! If there is anything wrong with my database design please let me know! thank you!

  Read the article

• database modeling for google app engine for multiple revison of entity.

  - by iamgopal

  hi, in my application ( kind of wiki clone ) - an article is frequently changing. and i need to track all changes that are done on that article. { text only. } one crude way i have done it, is to add a datetime property and create a new entity everytime something change. which is too much database wasting. { and also un-necessary index waste too. } and also need to re-create parent-child and entity relationships. i also have log which can show changes -- but i want some thing easier , so that jumping from one version to another version could be easier. ideas ? thanks.

  Read the article

• Merge Primary Keys - Cascade Update

  - by Chris Jackson

  Is there a way to merge two primary keys into one and then cascade update all affected relationships? Here's the scenario: Customers (idCustomer int PK, Company varchar(50), etc) CustomerContacts (idCustomerContact int PK, idCustomer int FK, Name varchar(50), etc) CustomerNotes (idCustomerNote int PK, idCustomer int FK, Note Text, etc) Sometimes customers need to be merged into one. For example, you have a customer with the id of 1 and another with the id of 2. You want to merge both, so that everything that was 2 is now 1. I know I could write a script that updates all affected tables one by one, but I'd like to make it more future proof by using the cascade rules, so I don't have to update the script every time there is a new relationship added. Any ideas?

  Read the article

• Foreign key on table A --> B, AND foreign key on table B --> A. How is this done?

  - by unclaimedbaggage

  Hi, I have two tables - 'business' and 'business_contacts'. The business_contact table has a many-to-one relationship with the business table. Furthermore, each business has a 'primary contact' field - which I'd assume is a one-to-many relationship with the business_contacts table. The problem, of course, is that this creates a catch-22 for data insertion. Since neither field can be null, I can't insert a business_contact until I have a corresponding business, but I can't insert a business until I have a corresponding business_contact. If anyone could help me get my head around how mutual one-to-many relationships are supposed to be dealt with I'd be most appreciative. (Project being done in MySQL if it makes any difference)

  Read the article

• Rails architecture questions

  - by justinbach

  I'm building a Rails site that, among other things, allows users to build their own recipe repository. Recipes are entered either manually or via a link to another site (think epicurious, cooks.com, etc). I'm writing scripts that will scrape a recipe from these sites given a link from a user, and so far (legal issues notwithstanding) that part isn't giving me any trouble. However, I'm not sure where to put the code that I'm writing for these scraper scripts. My first thought was to put it in the recipes model, but it seems a bit too involved to go there; would a library or a helper be more appropriate? Also, as I mentioned, I'm building several different scrapers for different food websites. It seems to me that the elegant way to do this would be to define an interface (or abstract base class) that determines a set of methods for constructing a recipe object given a link, but I'm not sure what the best approach would be here, either. How might I build out these OO relationships, and where should the code go?

  Read the article

• Design ideas for a versioned db schema with related tables also versioned

  - by vfilby

  Here is the drill, I want to version a database. I have done this before using multiple rows where the table primary key becomes a combination of the row id and either a datestamp or a version #. Now I want to version a table that depends on many other small tables. Versioning each table will be a giant PITA, so I am looking for good options to verion a schema where the data to be versioned spreads over multiple tables. All related tables are properly keyed with foreign key relationships. The database is currently on Sql Server 2005.

  Read the article

• Creating a view linking three different node types with two node references

  - by mikesir87

  I have the following content types: Camp - the top level type Registration Information - contains node reference to Camp called Camp Medical Release Form - contains node reference to registration information called Camper I would like to create a View that takes the nid for the Camp, and pulls out all the fields for the Registration Info and Medical Release Form. I'm having trouble figuring out how to set up the various arguments/relationships. I haven't done something that's referenced more than two types. I know it would be smart/best to just combine the Registration Info and Medical Release Form, since it's a 1:1 mapping, but we can't. So... any help would be appreciated!

  Read the article

• NSFetchedResultsChangeInsert reported when only updates are taking place

  - by niblha

  I have a class that acts as a NSFetchedResultsControllerDelegate which is receiving messages to -(void)controller:didChangeObject:atIndexPath:forChangeType:newIndexPath: with change type NSFetchedResultsChangeInsert, but the actual object which is the subject has with certainty not been newly inserted, only updated. So I would expect to get a change message with type NSFetchedResultsChangeUpdate, should I not? If i check the value of isInserted on the object, it yields false (as expected from the logic in my program). So my question is, why is this reported as an insert when it is only a change/update? They only thing I can think of is that part of the changes that are taking place is that objects of another entity type are inserted with relationships to objects of the entity type that the NSFetchedResultsController is set up to fetch.

  Read the article

• Rails 2.3.5: How does one add an error when it doesn't make sense to put it in a validation?

  - by randombits

  I recently was trying to add errors.add_to_base code in the middle of some model logic and was wondering why it wasn't showing up in my view that was iterating over all errors. I then ran across this e-mail which explains why: http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/e045ec1dead1ff06?pli=1 The question is then, how does one add errors with add_to_base if it doesn't make sense to put them into a validate method? I have some complex logic. The model needs to talk to a has_many relationship which has its own relationships that go through a myriad of conditionals to figure out if a request makes sense. It's nothing that can be tied to a validate method easily. How does one add errors then accordingly?

  Read the article

• Many-to-many relationship on same table with association object

  - by Nicholas Knight

  Related (for the no-association-object use case): http://stackoverflow.com/questions/1889251/sqlalchemy-many-to-many-relationship-on-a-single-table Building a many-to-many relationship is easy. Building a many-to-many relationship on the same table is almost as easy, as documented in the above question. Building a many-to-many relationship with an association object is also easy. What I can't seem to find is the right way to combine association objects and many-to-many relationships with the left and right sides being the same table. So, starting from the simple, naïve, and clearly wrong version that I've spent forever trying to massage into the right version: t_groups = Table('groups', metadata, Column('id', Integer, primary_key=True), ) t_group_groups = Table('group_groups', metadata, Column('parent_group_id', Integer, ForeignKey('groups.id'), primary_key=True, nullable=False), Column('child_group_id', Integer, ForeignKey('groups.id'), primary_key=True, nullable=False), Column('expires', DateTime), ) mapper(Group_To_Group, t_group_groups, properties={ 'parent_group':relationship(Group), 'child_group':relationship(Group), }) What's the right way to map this relationship?

  Read the article

• T-SQL Getting duplicate rows returned

  - by cBlaine

  The following code section is returning multiple columns for a few records. SELECT a.ClientID,ltrim(rtrim(c.FirstName)) + ' ' + case when c.MiddleName <> '' then ltrim(rtrim(c.MiddleName)) + '. ' else '' end + ltrim(rtrim(c.LastName)) as ClientName, a.MISCode, b.Address, b.City, dbo.ClientGetEnrolledPrograms(CONVERT(int,a.ClientID)) as Abbreviation FROM ClientDetail a JOIN Address b on(a.PersonID = b.PersonID) JOIN Person c on(a.PersonID = c.PersonID) LEFT JOIN ProgramEnrollments d on(d.ClientID = a.ClientID and d.Status = 'Enrolled' and d.HistoricalPKID is null) LEFT JOIN Program e on(d.ProgramID = e.ProgramID and e.HistoricalPKID is null) WHERE a.MichiganWorksData=1 I've isolated the issue to the ProgramEnrollments table. This table holds one-to-many relationships where each ClientID can be enrolled in many programs. So for each program a client is enrolled in, there is a record in the table. The final result set is therefore returning a row for each row in the ProgramEnrollments table based on these joins. I presume my join is the issue but I don't see the problem. Thoughts/Suggestions? Thanks, Chuck

  Read the article

• How to create relationship mapping via Entity framework

  - by James

  I have following domain model: User { int Id; } City { int Id; } UserCity { int UserId, int CityId, dateTime StartDate } In the function where I have to attach a user to a city, the following code is working for me: UserCity uc = new UserCity(); //This is a db hit uc.User = MyEntityFrameworkDBContext.User.FirstOrDefault(u => u.ID == currentUserId); //this is a db hit uc.City = MyEntityFrameworkDBContext.City.FirstOrDefault(c => c.ID == currentCityId); uc.StartDate = userCityStartDate; //this is a db hit MyEntityFrameworkDBContext.SaveChanges(); Is there any way I can create relationships with just one single DB hit? The first two db hits are not required, actually.

  Read the article

• What is an algorithm for minimizing some D distances between N items?

  - by Ross

  A classmate printed out a diagram of a database for class, the kind with lines representing relationships between tables. However, his lines crossed all over the place and it looked ugly. So I got to thinking about a way to move the tables to minimize the total line distance, and I couldn't think of a way to do it, other than just moving them all on top of each other. So basically: Given N items on some 2d coordinate space and some amount of connections between pairs of those items, how do you move the items so that the total distance between pairs is minimal, but that no distance is smaller than S? (so that the tables would not be too close together) Is there some algorithm for this? (I realize that smallest total distance won't necessarily make the layout less ugly; lines might still cross. But the table layout is just what got me thinking)

  Read the article

• has_many relation doesn't seems right or logical, some thing like belongs_to_many looks right

  - by Vijendra

  My situation is like this. Company has many users and users may belongs to many companies. And current implementation is something like below. class Company has_many :employments has_many :users, :through = :employments end class Employment belongs_to :company belongs_to :user end class User has_many :employments has_many :companies, :through = :employments #This doesn't looks correct end User has many companies doesn't looks logically meaningful.It must be some thing like belongs_to_many companies. Do I need to use has_and_belongs_to_many? But that also will gives the same meaning. Can some one please suggest the right way for representing these relationships?

  Read the article

• Javascript Library - Family Tree Flowchart

  - by MrMime

  Im looking for a simple Javascript Library (svg?) that allow me to draw a family tree relationships. I have searched a lot on google found a lot of interesting libraries like Raphaël and its extention Dracula. Google has its own library to make flowcharts too. Unfortunally, every library make a relation between nodes with a sigle line. If A and B has a relation to C, I will obtain 2 line: one from A to C and one from B to C. What I need is a line from A to B (we call it AB) and a line from AB to C to represent the Marriage of A and B. example-image Thanks.

  Read the article

• Hibernate - why use many-to-one to represent a one-to-one?

  - by aberrant80

  I've seen people use many-to-one mappings to represent one-to-one relationships. I've also read this in a book by Gavin King and on articles. For example, if a customer can have exactly one shipping address, and a shipping address can belong to only one customer, the mapping is given as: <class name="Customer" table="CUSTOMERS"> ... <many-to-one name="shippingAddress" class="Address" column="SHIPPING_ADDRESS_ID" cascade="save-update" unique="true"/> ... </class> The book reasons as (quoting it): "You don't care what's on the target side of the association, so you can treat it like a to-one association without the many part." My question is, why use many-to-one and not one-to-one? What is it about a one-to-one that makes it a less desirable option to many-to-one? Thanks.

  Read the article

• Show a django relationship in a template

  - by kevin_82

  I have a django model as follows: class Person(models.Model): name = models.CharField(max_length=255) class Relationship(models.Model): parent = models.ForeignKey(Person) child = models.ForeignKey(Person) description = models.TextField(blank=True) In my view, I pass a certain person, and the relationships in which he/she is parent: person = Person.objects.filter(name ='some name') descendant_relationships = Relationship.objects.filter(parent = person) An I want to show this person's descendants in a list in a template: <ul> {% for item in descendant_relationships%} <li> {{item.child.name}} - {{item.description}} </li> {% endfor %} </ul> But this template code will not show the children of children (i.e. grandchildren, great-grandchildren etc.). How can I get these lower level descendants to show up? I imagine recursion is necessary somewhere, but where?

  Read the article

• transform file/directory structure into 'tree' in javascript

  - by dave

  I have an array of objects that looks like this: [{ name: 'test', size: 0, type: 'directory', path: '/storage/test' }, { name: 'asdf', size: 170, type: 'directory', path: '/storage/test/asdf' }, { name: '2.txt', size: 0, type: 'file', path: '/storage/test/asdf/2.txt' }] There could be any number of arbitrary path's, this is the result of iterating through files and folders within a directory. What I'm trying to do is determine the 'root' node of these. Ultimately, this will be stored in mongodb and use materialized path to determine it's relationships. In this example, /storage/test is a root with no parent. /storage/test/asdf has the parent of /storage/test which is the parent to /storage/test/asdf/2.txt. My question is, how would you go about iterating through this array, to determine the parent's and associated children? Any help in the right direction would be great! Thank you

  Read the article

• How to organise a many to many relationship in MongoDB

  - by Gareth Elms

  I have two tables/collections; Users and Groups. A user can be a member of any number of groups and a user can also be an owner of any number of groups. In a relational database I'd probably have a third table called UserGroups with a UserID column, a GroupID column and an IsOwner column. I'm using MongoDB and I'm sure there is a different approach for this kind of relationship in a document database. Should I embed the list of groups and groups-as-owner inside the Users table as two arrays of ObjectIDs? Should I also store the list of members and owners in the Groups table as two arrays, effectively mirroring the relationship causing a duplication of relationship information? Or is a bridging UserGroups table a legitimate concept in document databases for many to many relationships? Thanks

  Read the article

< Previous Page | 24 25 26 27 28 29 30 31 32 33 34 35  | Next Page >