lsp association

= hibernateutils.getsession (); session.begintransaction (); person person = (person) session.load (person.class,5); system.out.println (Person.getname ()); system.out.println (Person.getidcard (). Getcardno ()); session.gettransaction (). commit (); }catch (Exception e) { e.printstacktrace (); session.gettransaction (). rollback (); }finally{ hibernateutils.closesession (session); } } Load the Idcard object first, and then load the person objectpublic void TestLoad2 () {Sess

One -to-one mapping in the object model is often seen, mainly to transform the object model into a relational model must be configured in the mapping file, focusing on the use of A primary key Association in a one-to-one association map, which means that two objects have the same primary key value to indicate a one by one corresponding relationship between them, and the database table does not have additio

A commonplace question. Recently, through the feedback in the group, I feel that many people still do not understand the problem. To get this problem clear today, let's see how Yii2 ActiveRecord is associated with multiple tables and how to optimize this association.Scenario Requirements:Suppose we have a user table and a user channel table Auth, and two data tables are one-to-one by User.ID and Auth.uid. You now need to show source channel sources for the Auth table in the user list, and the ch

Hibernate Association ing and hibernate Association ing Relationship between entitiesAssociation, aggregation, dependency, combination, inheritance Link Type:One-to-multipleMany-to-oneOne-to-oneMany-to-many Student table and grade Table: 1 -- student table 2 create table student (3 stuno number (4) primary key, 4 name varchar2 (20) not null, 5 gradeid number (4) 6 7) 8 -- grade table 9 create table grade

For two tables, is it generally a direct association or two queries, such as a user table or a user education table {code? Isn't it possible to directly associate the database? Is it possible to allow php to join the database more than once? For other tables, such as busy businesses or services... for two tables, it is usually directly associated or found twice before association, such as user tables and us

Laravel Association between models of different databases, Laravel Model Association Suppose the relationship between Modela and Modelb is Belongsto. If you belong to a database connection So Public function A () { return$this->belongsto ("Modela") } If two models belong to a different database So Public function A () { $instancenew Modela; $instance->setconnection ($a _conn);

Yii2: one-to-one data table Association; yii2: one-to-one Association 1. Create two tables publish: pub_id and images: pub_id and image_path;2. Use crud of gii to generate code3. Write the association function in Publish. php In models. public function getImage() { return $this->hasOne(Images::className(),['pub_id'=>'pub_id']); } 4. Write the joinWi

One-Way N ---> 1 Association. For example, if multiple people correspond to the same address, you only need to find the corresponding address entity from the physical end, so you do not need to care about all the residents of a specific address. To enable two persistence classes to support this association ing, the program should add an attribute to the persistence class at one end of N, which references th

The associasion element is required for MyBatis to handle the "one-to-many" relationship. Processing "Many-to-one" is implemented with the collection element (these two elements are mentioned in the previous mapper file).In this example, suppose that a user can have multiple orders and use Associasion to implement association relationshipsFirst, the database table structureCREATE TABLE ' user ' (' ID 'int(8) not NULL auto_increment, ' username ' varch

Hibernate (8) one-to-many Association and hibernate Association 1. One-to-multiple one-way Guan Liang One-to-multiple unidirectional Association is similar to multiple-to-one association. Assume that a Group has multiple users, that is, one (Group) to multiple (User) You need to add a Set for the User class to the Grou

Based on the primary key mapping 1-1 correlation relationship and based on the foreign key mapping 1-1 correlation relationship, the main difference is that the configuration map file will be differentTwo persistence classes for manager and department1: Based on primary key mapping 1-1 Association relationship1) mapping files for entities that generate primary keys using the primary key of other persisted classes first need to specify a primary key ge

The ActiveRecord of Yii is the class that deals with the database, the M (model layer) in MVC, and the Orm O (Object). A commonplace question. Recently through the group of feedback, feel that many people still do not understand this problem. Let's get this over with today and see how the Yii2 ActiveRecord is a multiple-table association and how to optimize the association. Scenario Requirements: Let's s

Database Single Table association implements data count function (table itself association)Note: This blog post for the original blogger, please indicate the source of reproduced.　　　　question : In the database there is such a table, which mainly contains three fields, GOODSID (cargo number), TypeId (type number), State (status). The cargo number is not duplicated, goodsid and typeid belong to N to 1 relatio

Description of Entity notes corresponding to the automatic association query and automatic association update navigation properties of Entity Framework, entityframework I. First, I want to know about the automatic association query of Entity Framework: Automatic association query of Entity Framework. Three methods are

Save the Association as a table and store the foreign key of the associated table In an object, a collection is used as a domain value to handle multiple domains. In db, there can be only a single domain value. The core of the foreign key mapping is the use of foreign keys to maintain contact on the single-valued side of the association relationship. In many-to-many relationships, there is no

. // Constructors 20. 21. /** default constructor */ 22. public Husband() { 23. } 24. 25. /** minimal constructor */ 26. public Husband(String name) { 27. this.name = name; 28. } 29. 30. /** full constructor */ 31. public Husband(Wife wife, String name) { 32. this.wife = wife; 33. this.name = name; 34. } 35. 36. // Property accessors 37. 38. public Integer getId() { 39. return this.id; 40. } 41. 42. publ

Reprinted from: http://blog.csdn.net/blucexi/article/details/1253265 Joint editingThat is, the process of generating executable code by combining modules and functions, allocating memory addresses for each module or function call, and allocating the correct memory addresses for external access, it is a process in which computer programs are associated with each other. There are two different association methods according to different stages of

Hibernate a pair of unique foreign Key Association Mappings (Bidirectional Association person One-to-one unique foreign Key association bidirectional, required on the other end (Idcard), adding The associated object, by default, is loaded by the primary key person, in the Foreign Key association mapping, because two

Multi-to-many unidirectional Association and multi-to-one Association One Teacher (Teacher) teaches multiple students, and one Student (Student) can have multiple teachers (Teacher). This is a one-to-one relationship, the following example is used for Configuration: Annotataion Configuration: Teacher: 　　　　　　 1 package com.bjsxt.hibernate; 2 3 import java.util.HashSet; 4 import java.util.Set; 5 6 import j

Cross-database association query method in mysql, mysql cross-database Association Business scenario: Associate queries for tables in different databases For example, the table to be associated is: Table A in database A on machine A table B in database B on machine B. In this case, you want to execute "select A. id, B. id from A left join B on ~~~; "That's impossible, but the business needs are immutable,