many-to-many

many-to-many mapping in NHibernate

由 本小妞迷上赌 提交于 2019-11-29 03:14:23
问题 I'm looking to create a many to many relationship using NHibernate. I'm not sure how to map these in the XML files. I have not created the classes yet, but they will just be basic POCOs. Tables Person personId name Competency competencyId title Person_x_Competency personId competencyId Would I essentially create a List in each POCO for the other class? Then map those somehow using the NHibernate configuration files? 回答1: You can put the many-to-many relation to either class, or even to both.

Insert operation with many-to-many relationship using EF

由 青春壹個敷衍的年華 提交于 2019-11-29 03:05:25
问题 I've two model classes: public class Candidate { public int Id { get; set; } public string Name { get; set; } public ICollection<Job> Jobs { get; set; } } public class Job { public int Id { get; set; } public string Name { get; set; } public ICollection<Candidate> Candidates { get; set; } } My DbContext name is JobsContext. The above code generates me 3 tables Candidates, Jobs & CandidatesJobs(autogenerated by EF) Now I've records in Jobs table : Id = 1, Name = "Sales" : Id = 2, Name =

Query examples in a many-to-many relationship

由 倾然丶 夕夏残阳落幕 提交于 2019-11-29 03:00:59
问题 Wow, it's hard to find a simple explanation to this topic. A simple many-to-many relationship. Three tables, tableA, tableB and a junction tableA_B. I know how to set up the relationship, with keys and all, but I get a little confused when time comes to perform INSERT, UPDATE and DELETE queries.... Basically, what I am looking for is an example that shows: How to get all records in TableA, based on an ID in TableB How to get all records in TableB, based on an ID in TableA 3 How to INSERT in

MySQL many-to-many relationship with FOREIGN KEYS

由 99封情书 提交于 2019-11-29 02:51:57
问题 I am trying to create a many-to-many relationship in my MySQL database. I have three tables: Films , Genres and Films_Genres . I am using the following code to set them up: CREATE TABLE Films ( id INT NOT NULL AUTO_INCREMENT, PRIMARY KEY(id), Title VARCHAR(255) ), CREATE TABLE Genres ( id INT NOT NULL AUTO_INCREMENT, PRIMARY KEY(id), Name VARCHAR(255) ), CREATE TABLE Films_Genres ( film_id INT NOT NULL, genre_id INT NOT NULL, PRIMARY KEY (film_id, genre_id), FOREIGN KEY (film_id) REFERENCES

How do you do many to many table outer joins?

由 China☆狼群 提交于 2019-11-29 02:32:44
问题 I have 3 tables, foo, foo2bar, and bar. foo2bar is a many to many map between foo and bar. Here are the contents. select * from foo +------+ | fid | +------+ | 1 | | 2 | | 3 | | 4 | +------+ select * from foo2bar +------+------+ | fid | bid | +------+------+ | 1 | 1 | | 1 | 2 | | 2 | 1 | | 2 | 3 | | 4 | 4 | +------+------+ select * from bar +------+-------+------+ | bid | value | zid | +------+-------+------+ | 1 | 2 | 10 | | 2 | 4 | 20 | | 3 | 8 | 30 | | 4 | 42 | 30 | +------+-------+------+

jpa criteria for many to many relationship

由 血红的双手。 提交于 2019-11-29 02:23:22
问题 I have 2 POJO classes in Java, Answer and Collaborator, in a many-to-many relationship. class Answer { @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "ANSWERS_COLLABORATORS", joinColumns = { @JoinColumn(name = "aid") }, inverseJoinColumns = { @JoinColumn(name = "cid") }) private Set<Collaborator> collaborators = new HashSet<Collaborator>(0); } Class Answer has a set of Collaborator , but a Collaborator doesn't keep a set of Answer . What I need to do from Hibernate CriteriaQuery is

Hibernate many to many - fetch method eager vs lazy

由 本秂侑毒 提交于 2019-11-29 02:07:35
New to Hibernate. I have User Group many to many relation. Three tables : User , Group and UserGroup mapping table. Entities: @Entity @Table(name = "user") public class User { @Id @Column (name = "username") private String userName; @Column (name = "password", nullable = false) private String password; @ManyToMany(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER) @JoinTable(name="usergroup", joinColumns={@JoinColumn(name="username")}, inverseJoinColumns={@JoinColumn(name="groupname")}) private Set<Group> userGroups = new HashSet<Group>(); ... setter and getters @Entity @Table(name = "group

NHibernate 3.2 many to many mapping by code

由 房东的猫 提交于 2019-11-29 02:01:33
I'm trying to learn NHibernate 3.2 built-in mapping by code api ( NOT FluentNHibernate, nor xml). Can you help me to map a many-to-many relationship between these entities please? public class Post { public virtual Id { get; set; } public IList<Tag> Tags { get; set; } } public class Tag { public virtual Id { get; set; } public IList<Post> Posts { get; set; } } My primary key strategy is: Id( t => t.Id, t => { t.Generator(Generators.HighLow, g => g.Params(new { max_low = 100 })); t.Column(typeof(TEntity).Name + "Id"); }); and I try this: // TagMap : ClassMapping<Tag> Bag(t => t.Posts, bag => {

Java many to many association map

由 主宰稳场 提交于 2019-11-29 01:57:06
I have two classes, ClassA and ClassB , as well as a "many to many" AssociationClass . I want a structure that holds the associations between A and B so that I can find the counterpart for each instance of A or B. I thought of using a Hashmap, with pair keys: Hasmap<Pair<ClassA, ClassB>, AssociationClass> associations; This way, I can add and remove an association between two instances of ClassA and ClassB , and I can query a relation for two given instances. However, I miss the feature of getting all associations defined for a given instance of ClassA or ClassB . I could do it by brute force

How to build many-to-many relations using SQLAlchemy: a good example

由 一曲冷凌霜 提交于 2019-11-29 01:17:45
问题 I have read the SQLAlchemy documentation and tutorial about building many-to-many relation but I could not figure out how to do it properly when the association table contains more than the 2 foreign keys. I have a table of items and every item has many details. Details can be the same on many items, so there is a many-to-many relation between items and details I have the following: class Item(Base): __tablename__ = 'Item' id = Column(Integer, primary_key=True) name = Column(String(255))
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