jointable

问题 I am new to programming & rails and there's something I dont fully understand. I am creating an app with product has_many categories category has_many products If I understand correctly I need to create a join table products_categories which has a product_id & a category_id . First do I also need a model for this table ? if yes I guess it would look like this : class CategoryProduct < ActiveRecord::Base belongs_to :category belongs_to :product end and the other models in product.rb : class

问题 There are 3 tables: TABLE_A ID_A field1 fieldN TABLE_B ID_B field1 fieldN TABLE_A_B ID_A ID_B orderField public class A(){ @ManyToMany @JoinTable(name="TABLE_A_B", joinColumns={@JoinColumn(name="ID_A")}, inverseJoinColumns={@JoinColumn(name="ID_B")}) @OrderBy(value="orderField") private List<TABLE_B> BList; } But it isn't working, instead I get a runtime error: Caused by: org.postgresql.util.PSQLException: ERROR: column B1_.orderField doesn't exist Position: 1437 Hibernate searches the field

问题 I've got two tables and a join table: 'staff', 'classification' and 'staff_classification'. In the join table I've got an extra boolean field: 'showclassification'. My annotation is as follows: /** * @ManyToMany(targetEntity="Staff", inversedBy="classifications") * @JoinTable(name="staff_classifications", * joinColumns={@JoinColumn(name="staffid", referencedColumnName="id")}, * inverseJoinColumns={@JoinColumn(name="classificationid", referencedColumnName="id", unique=true)}); */ How do I add

问题 I have four entities that I would like to translate into database tables via code first fluent api (I'm using a model found at databaseanswers.org), but I'm not certain as to how. The problem I'm having is that SuggestedMenuId is being migrated across two different tables in a Composite key (MenuCourse and CourseRecipeChoice). Here's the message I'm getting: "One or more validation errors were detected during model generation: \tSystem.Data.Entity.Edm.EdmAssociationConstraint: : The number of

问题 I have spent couple of hours searching around and did not found anything similar to my case. Let's assume following many-to-many data model: Contract (any business entity) - contract_id - other fields Party (another business entity) - party_id - other fields Contract_Party (relations between first two with additional role indicator, e.g. owner, signer, seller, etc) - contract_id - party_id - role Now let's assume I want to map all contracts related to party (uni-directional). It can be done

问题 can I get data like this from my table | id_outlet| date | count(msisdn) | | 34.10.1 | 2014-08 | 0 | | 34.10.1 | 2014-09 | 3 | | 34.10.1 | 2014-10 | 2 | | 34.10.2 | 2014-08 | 1 | | 34.10.2 | 2014-09 | 0 | | 34.10.2 | 2014-10 | 0 | So I have 2 tables 1. table outlet (unique) 2. table sales (detail of table outlet) As u see in my second table there are 3 periode (2014-08, 2014-09, 2014-10) I want join that periode with id_outlet in first table like that example. Can I? Please Help me 回答1: Using

问题 I'm mapping a proprietary database to Hibernate for use with Spring. In it, there are a couple of jointables that, for entity A and entity B have the following schema: CREATE TABLE AjoinB ( idA int not null, idB int not null, groupEnum enum ('groupC', 'groupD', 'groupE'), primary key(idA, idB, groupEnum) ); As you can see, this indicates that there can be multiple A-B relationships that put them in different groups. I'd like to end up with, first line for entity A and second for entity B, the

问题 Problem I am coding proof of concept ASP.NET 5 MVC6 that will simulate a library. I am using CTP6 and beta3. How to define their relationship in Entity Framework 7 using code first approach? Shelf and Books need a join table. As I see it, this application will consider one shelf at a time and the books on that self. In other words, one shelf has a one to many relationship with books. Models Shelf model: public class Shelf { public int ShelfId { get; set; } public string ShelfName { get; set;

问题 I have 2 tables (simplified for this example) which I want to join in a particular way. Table 1 (ae) has subject number, ae term Table 2 (mh) has subject number, mh term heres the construct to help INSERT INTO ae VALUES ('0001-0012','DRY EYE (12 OCT 2017)'); INSERT INTO ae VALUES ('0001-0012', 'DEPRESSION (7 OCT 2017)'); INSERT INTO ae VALUES ('0001-0013','SKIN ATROPHY, LEFT UPPER ARM (4 OCT 2017 )'); INSERT INTO mh VALUES ('0001-0012', 'DIABETES MELLITUS (UN JUL 2007)'); INSERT INTO mh

问题 I have a situation that is quite similar to the one outlined in this question's diagram: JPA. JoinTable and two JoinColumns, although with different issues. I have three tables: Function , Group , and Location . Currently, I have a join table set up between Location and Group using @JoinTable . It is @ManyToMany on both sides, and works perfectly fine. I am attempting to add the constraint that no Location should be associated with more than one Group that has the same Function . So I added a