many-to-many

问题 I'm extremely new to Dynamic Data, but I'll fire this off anyway. I have an EF model set up, with a PJT table linking Shows and Genres. The EDMX correctly displays this as a * - * relationship between Shows and Genres, with navigation properties. Using Dynamic Data, I can create a Show item, but then only once it is created, can I edit it to link up the Genres (which are nicely displayed as check boxes). I've read this http://blogs.msdn.com/b/davidebb/archive/2008/10/25/a-many-to-many-field

问题 Assuming a pure many to many where the primary key is the composite of two foreign keys. For example "Employee Privileges" in Northwind has EmployeeID and PrivilegeID. This m2m obviously relates the Employees table to the Privilege table. I need to write a query with EF that returns all Employees that are NOT associated with a specified PrivilegeID, regardless of whether or not it is related to other PrivilegeIDs. I have an EF query that works for Sql Server using Except() but it doesn't work

问题 I've got a site where people record game results. 95% of the games are played solo, but the 5% that aren't throw off the win-draw-win statistics for each scenario. Each battle has 2 sides, and all possible results are: Side 1 wins Side 2 wins Draw If 2 people play each other, and both record a play, you get 2 wins for a given side when there should only be one, (making sense?) and it throws off the balance rating. Those records should be merged when it comes time to display the battle's stats

问题 I have a model class dietplan in which there is a many-to-many field named breakfast. In my view.py I have done some calculation and get a value for breakfast as nested list i.e. [['abc','asda'],['val3','val4']] I want to these all 4 list in my many to many field. This is my code: MODELS.PY\ class Dietplan(models.Model): user = models.OneToOneField(User, on_delete=models.CASCADE) dietplan_name = models.CharField(max_length=255, null=True) breakfast = models.ManyToManyField('Meal', related

问题 Here is the situation: I have a model as below: class School(Model): name = CharField(...) Permit model has three objects: School.objects.create(name='school1') # id=1 School.objects.create(name='school2') # id=2 I have another model: Interest(Model): school_interest = ManyToManyField(School, blank=True,) I then build a ModelForm using Interest: class InterestForm(ModelForm): school_interest = ModelMultipleChoiceField(queryset=School.objects.all(), widget=CheckboxSelectMultiple, required

问题 How to Show Multi ( Teams ) Results ( Players ) in Posts I Already got one post and both Multi Teams of this post like in this pic !!! My previous question you can check out is How to use Many to Many Relationship posts#show In ruby on rails. Now I use Teams and Players like this: In Players#Model class Player < ActiveRecord::Base belongs_to :team end In Teams#Model class Team < ActiveRecord::Base has_many :players has_many :postteams has_many :posts, :through => :postteams end In Postteam

问题 The following tables are given: --- player -- id serial name VARCHAR(100) birthday DATE country VARCHAR(3) PRIMARY KEY id --- club --- id SERIAL name VARCHAR(100) country VARCHAR(3) PRIMARY KEY id --- playersinclubs --- id SERIAL player_id INTEGER (with INDEX) club_id INTEGER (with INDEX) joined DATE left DATE PRIMARY KEY id Every player has a row in table player (with his attributes). Equally every club has an entry in table club. For every station in his career, a player has an entry in

问题 I have TableA in a many-to-many relationship with TableC via TableB. That is, TableA TableB TableC id | val fkeyA | fkeyC id | data I wish the do select sum(val) on TableA, grouping by the relationship(s) to TableC. Every entry in TableA has at least one relationship with TableC. For example, TableA 1 | 25 2 | 30 3 | 50 TableB 1 | 1 1 | 2 2 | 1 2 | 2 2 | 3 3 | 1 3 | 2 should output 75 30 since rows 1 and 3 in Table have the same relationships to TableC, but row 2 in TableA has a different

问题 Does anyone know what I should put in the empty fields below to make this relationship work out of the box? I am very close to making this work as all associations work flawlessly. The only issue is that I cannot save a user with fruits attached to it as, currently, there is no :inverse_of. I need the :inverse_of pointing in the right direction so that I can save a user with fruits instead of having to save the user first and then attach fruits to it later. Thank you! UPDATED AFTER COMMENTS:

问题 I am developing for an existing application which uses a SQL database that is used by two applications. One uses Entity Framework to connect to the database. The other uses LINQ-to-SQL. The SQL database is designed so that there are some tables showing many-to-many relationships between rows in two tables. Entity Framework seems not to import these tables, apparently because it has some object-oriented idea for how many-to-many relationships ought to be represented. So far, the Entity