relationship

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HABTM Polymorphic Relationship

I\'m pretty new to Rails, and i\'m trying to do a polymorphic HABTM relationship. The problem is that I have three models that I want to relate.[详细]

2023-03-26 21:44 分类：问答
My NSManagedObject has 2 To－Many relationship， but only one can return correct class information

My NSManagedObject says Tag has 2 To－many relationships，says posts and children. And I let Xcode 4 to generate NSManagedObject subclass for it.But I find that only one relationship can return the co[详细]

2023-03-26 10:36 分类：问答
Accessing a table in Ruby on Rails via relationship

I\'m trying to build an inventory system for the various servers and apps we have. I have the following tables/Models:[详细]

2023-03-25 23:13 分类：问答
Error writing to an XML file a dataset with multiple Related Tables and not enforcing constraints

Does any body know how to write an XML from a Dataset that has multiple tables with multiple parent rows?[详细]

2023-03-25 06:23 分类：问答
What is the best way to represent a constrained many-to-many relationship within a relational database?

I would like to establish a many-to-many relationship with a constraint that only one or no entity from each side of the relationship can be linked at any one time.[详细]

2023-03-24 16:36 分类：问答
Show all relationships between two columns in MySQL

I have a single table that has data like the following: Column 1 -- Column 2 A -- Z A -- Y B -- Y I am looking for a way in MySQL to roll up this data so that I get the following table that will[详细]

2023-03-24 02:34 分类：问答
Grails - testing GORM relationships

Bit of a newbie to Grails here. I have 2 domain objects linked with a hasMany relationship like so: class Accommodation[详细]

2023-03-23 18:36 分类：问答
FileMaker Pro Conditional Relationship Not Working

When I v开发者_如何学编程iew table \"Invoice Check Groupings\" in list or table model, all records from Invoice appear, not just those matching the global field \"Blank Invoice Check Grouping\"\'s val[详细]

2023-03-23 14:17 分类：问答
How to find sqlalchemy remote side object's class or class name without db queries?

Let\'s have a classes X and Y and relations between them x2y and y2x. From class_mapper(Class).iterate_properties iterator we can get all class\'s properties.[详细]

2023-03-23 10:18 分类：问答
Creating a one-to-one relation for a pre-existing record using Doctrine ORM (1.2)

Background / Application I have two database tables, supplier and address with a one-to-one relationship, as not all suppliers have an address (and this is just a simplified example from a larger app[详细]

2023-03-23 02:49 分类：问答