composite-key

问题 I've got database tables like this: A person may be a member of many teams. A team may have many members. Each person may have a position (think job title) within the team. I've tried to set this up with ADO.NET Entity Framework and get errors: Error 3021: Problem in mapping fragments starting at line ... Each of the following columns in table Membership is mapped to multiple conceptual side properties: Membership.PersonId is mapped to <MembershipPerson.Membership.PersonId, MembershipPerson

问题 I have a composite key entity where one property is an int, and the other is an enum. The enum is currently mapping by string, but it needs to be int. I have an IUserTypeConvention that already does this, but it doesn't work for composite keys. I have an Accept() method that correctly locates composite keys with enums in it, but I cannot figure out the Apply() code. public class CompositeKeyEnumConvention : ICompositeIdentityConvention, ICompositeIdentityConventionAcceptance { public void

问题 I don't know if I'm missing something obvious, but I really want to grab names of clients associated with a composite key. Controller Code: Job job = db.Jobs.Find(id); ViewBag.jobClientsList = new SelectList(job.JobClients.ToList(), "ClientNumber", "ClientNumber"); View Code: <%: Html.DropDownList("ClientNumber", ViewData["JobClientsList"] as SelectList)%> Model: namespace Sample.CustomerService.Domain { using System.ComponentModel.DataAnnotations; public class JobClient { public JobClient()

问题 I am unable to pass a composite key to a MyBatis <collection> element (using version 3.2.7). The MyBatis documentation states: Note: To deal with composite keys, you can specify multiple column names to pass to the nested select statement by using the syntax column="{prop1=col1,prop2=col2}". This will cause prop1 and prop2 to be set against the parameter object for the target nested select statement. However, all my attempts to implement this produce the Exception org.mybatis.spring

问题 I have faced some issue while creating JPA Composite Key with Object references. Entities are as show in bellow, 1) I wan to remove the ID field from Workflow entity and make a composite key with combining seqNo field and template (object reference) field 2) According to that change updated the existing relationship with Command entity (@JoinColumn(name = "WORKFLOW_ID", referencedColumnName = "ID")) Thanks. Template entity: @Entity @Table(name = "template") public class Template implements

问题 I have the following model (ignoring irrelevant/obvious code, like setters and getters): @Entity public class Invoice { @Id // sequence generated private Long invoiceId; @OneToMany(fetch = FetchType.EAGER) @JoinColumn(name = "invoiceId", referencedColumnName = "invoiceId") @OrderBy("id.itemNumber") List<Item> items = new ArrayList<Item>(); } @Entity public class Item { @EmbeddedId private ItemPK id; } @Embeddable public class ItemPK { private Long invoiceId; private Long itemNumber; } Can't

问题 I am creating an application that will handle and record when a student gets advised by a faculty member at a university and I need an effective way to structure the tables. My problem is coming from a lack of referential integrity, caused by the inability to create a foreign key that will reference a STUDENT on only part of a composite key in ADVISE_HIST which is (STUDENT_ID,DATE_ADVISED) here are some of the tables create table STUDENT( LNAME varchar(50), FNAME varchar(50), ID char(9)

问题 Does anybody knows any performance issues in using composite-ids, whether @EmbeddedId or @IdClass , with Hibernate? Thanks. 回答1: In my opinion, Hibernate itself does not have significant performance impact whether its a composite key or not. what matters is the dbms, engine type, queries, number of updates on table, indexes and types of columns. Hibernate will just be translating hql into sql, so in this case performance of hibernate should be good if underlying queries perform good.... here

问题 I am bit confused on making a good relational database. I am using phpmyAdmin to create a database. I have the following four tables. Don't worry about that fact place and price are optional they just are. Person (Mandatory) Item (Mandatory) Place (Optional) Price (Optional) Item is the main table. It will always have person linked. * I know you do joins in mysql for the tables. If I want to link the tables together I could use composite keys (using the ids from each table), however is this

问题 I am trying MapReduce program in MongoDB, I have MongoDB collection with following data type: { "_id" : ObjectId("57aea85af405910cfcd2bfeb"), "friendList" : [ "Karma", " Tom", " Ram", " Bindu", " Shiva", " Kishna", " Bikash", " Bakshi", " Dinesh" ], "user" : "Hari" } { "_id" : ObjectId("57aea85bf405910cfcd2bfec"), "friendList" : [ "Karma", " Sita", " Bakshi", " Hanks", " Shyam", " Bikash" ], "user" : "Howard" } { "_id" : ObjectId("57aea85cf405910cfcd2bfed"), "friendList" : [ "Dinesh", " Ram",