foreign-key-relationship

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Designing without duplicate foreignkey references in Django

I want to create an expense tracking application, where each user can enter expenses and classify them into his own categories. Here is the model definition that I use:[详细]

2023-03-14 19:40 分类：问答
Save has_and_belongs_to_many link in basic RoR app

I try to learn the has_and_belongs_to_many relationship between my 2 fresh new and simple models Product and Author, where a Product can have many authors and where author can have a lots of products.[详细]

2023-03-14 13:31 分类：问答
RoR "Has many" link > How to get title via foreign key?

I have a basic question of relationship in RoR : In a view, I try to display the t开发者_C百科itle of a group, which is in the table \"groups\", and only the key \"group_id\" is stored in the table/o[详细]

2023-03-14 09:38 分类：问答
DB project - improving performance with relationships

I have two tables, let\'s call them TableA and TableB. One record in TableA is related to one or more in TableB. But there\'s also one special record within them in TableB for each record from TableA[详细]

2023-03-13 16:35 分类：问答
Get one comment table to serve both apps and posts table?

I\'ve created a table called comments, comments has a property called ItemId which is used as the foreign key for two other tables posts and apps.[详细]

2023-03-13 07:37 分类：问答
many-many model join with SQLAlchemy

I\'m having the worst time trying to get a many-many join to work using models in SQLAlchemy.I\'ve found lots of examples online, but I can\'t ever seem to figure out if their strings represent the co[详细]

2023-03-13 06:23 分类：问答
Is this record related to me?

I have two models that are related to each other. For a contrived example, the first is a list of things and the second is a list of people who have liked each thing.[详细]

2023-03-12 11:25 分类：问答
active record where foreign key can be anything of two columns

I have a User Model. I have a Friend Model with columns invitee_id and Inviter_id and status. Status is used as flag whether friend request has been accepted or not. Inviter_id is the id of the user[详细]

2023-03-12 10:01 分类：问答
LINQ to SQL: Updating fields based on foreign key relations during creation of new entities

I\'m using WPF and Xaml I\'m creating a new row into a table. That table has a foreign key relationship. When the user types in the FK field I wan\'t others to update based on the relations. This I d[详细]

2023-03-11 11:14 分类：问答
foreign key to non candidate key and on delete cascade

My question i开发者_如何学JAVAs two fold, firstly, is it possible to create a foreign key,in mysql, from a referencing table to a column in the referenced table that is not a candidate key ? I tried[详细]

2023-03-11 04:06 分类：问答