entity-relationship

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Create Entity Associations on Non Key Columns

I have two tables Users and Schools. Each have primary keys and no foreign keys. The database I have to tie in has no normalization at all, but I still have to have associations in it.[详细]

2023-03-01 16:01 分类：问答
Custom setter for Core Data relationship to force inverse, reciprocal relationship

I want to create a custom setter for an NSManagedObject core data one-to-many relationship (Object.related), so that when object A is added to B.related, B is automatically added to A.related, and if[详细]

2023-03-01 08:44 分类：问答
How to emulate "extending a class" with database tables?

I will have several different types of users that will use my system. For all users I need to store such things as username, password, email address, etc, but if they are a user of category A, I also[详细]

2023-03-01 06:03 分类：问答
unify two models (edmx) with visual studio 2010

Hello as actually as i know you can not make relations between tow models or have in one models entities from two databases, it\'s a posibility two join two models both of them with existig databases[详细]

2023-03-01 03:05 分类：问答
How to get the social map of friends by a single query from a social networking sql database?

I have a social networking site built on top of the Elgg (php + mysql) framework. My objective is to get all friends of a given user, and also the friend relationships among those friends.[详细]

2023-03-01 01:28 分类：问答
Linq to SQL - Possible to generate Unique Key constraint on DB via entity attribute

In Linq to Sql, Is there any way to define attributes on an entity that indicate that it should be unique (a开发者_如何学运维nd will also generate a unique constraint in the database when generating t[详细]

2023-02-28 23:56 分类：问答
Entity Model Help

I have the following model in my database, but I\'m a bit confused on what I 开发者_StackOverflow社区should do.[详细]

2023-02-28 20:41 分类：问答
Core Data: Can I add a relationship to the parent entity?

I made the Photo entity, which has a Data attribute to store the image data. Photo is the parent of the Thumbnai开发者_高级运维l entity. I also added a one-to-one relationship between Photo and Thumbn[详细]

2023-02-28 16:35 分类：问答
Like button doesn't refresh to unlike but the relationship is created in the model

Hi I\'ve set set of an appreciation controller that handles user\'s liking different posts. Each post has a like button and when I click it looks like the request goes through but the page doesn\'t re[详细]

2023-02-28 06:29 分类：问答
Putting everything in the relationships model or adding a new model

I followed the Michael Hartle book Rails Tutorial and made 开发者_如何学Pythona user following system that works through a relationships table, with a follower_id and a followed_id.[详细]

2023-02-28 05:43 分类：问答