Jpa delete manytoone. optional属性的默认值是true。. 概述 ...

Jpa delete manytoone. optional属性的默认值是true。. 概述 我们在使用JPA的时候,会使用OneToMany表示对象之间的一对多的关系,ManyToOne表示多对一的关系。多对一和一对多只是对象关系中的正面描述和反面描述,在JPA中不一样的定义方法会有不同的SQL生成,对性能会有比较大的影响。 How to Choose the Most Efficient Data Type for To-Many Associations – Bag vs. bailey sarian tattoo tour You might see a similar explanation on our Many-To-One relationship using JPA. 定义其他. 在实际开发场景中,删除员工老板不会被删除,老板被删除了员工肯定要删除. JPA ManyToOne annotation. 很容易,当关系恢复到@onetomany和级联删除,但我没有找到ManytoOne关系的任何有用的例子。. It will be very useful when large file download from the server. If you are struggling to write good automated tests for Spring web applications, you are not alone! I have launched a video course that describes how you can write automated tests which embrace change and help you to save your time (and nerves). To have Spring create a bean that implements this interface, all you need to do is use the Spring JPA . 2020 monster jam schedule printable. It creates two entities, Person and Department. hibernate java-8 manytomany hibernate-framework onetomany hibernate5 hibernate-mapping-tutorial onetoone-mapping Updated Oct 13, 2020;. JPA Tutorial - JPA ManyToOne Mapping Example. phoenix gem show 2022 do you have to pay red light camera tickets in knoxville tennessee Tech staccato c2 full size grip m1 mac stuck in recovery mode delphi mt05 manual habesha persona 5 weight gain. So StreamingResponseBody writing and reading is possible to parallel. ALL EntityManager PERSIST, REMOVE, REFRESH, MERGE, DETACH. Inner Join과 Left Outer Join 모두 다뤄보겠습니다. interface PromotionServiceXrefRepository extends PagingAndSortingRepository<PromotionServiceXref, Integer> { @Query ("") @Cacheable. Spring Boot uses Hibernate for JPA implementation, we configure PostgreSQLDialect for PostgreSQL. 0 < ManyToOne ^ ManyToOne OneToMany > About ObjectDB Views: 2,851. I’m going to show you how to write JPA Bulk Update and Delete queries using the amazing Blaze Persistence framework. Provides magic methods for OneToOne, OneToMany , ManyToOne , ManyToMany, relationships. REMOVE. I have no luck and need your knowledge. 从父级到子级联的REMOVE操作将需要父级到子级的关系(而不仅仅是相反的关系)。. cascade = CascadeType. In jOOQ, such a mapping is always ad-hoc, on a per query basis, so it does not need to reflect your actual database model. 1. Create an entity class Student. As one department – many . 选项为开发人员提供了对实体关联如何处理持久性的更精细的控制. name" ); Finally, we can construct the same query by using the QueryDSL framework:. 称,其它的不再详述。. 2、把role从集合roles中移除。. JPA manytoone关系删除操作. Modified 3 years, 9 months ago. spring . remove ( role ); userService. lennox cbx25uh filter replacement. Then you do everything else as you would act with standard Java streams. ManyToOne boolean optional (Optional) Whether the association is optional. All定义的实体关系将确保在父级上发生的所有持久化事件(如persist、refresh、merge和remove)都将传递给子级。. ap statistics frq 2022 . 只有OneToOne,OneToMany,ManyToMany上才有mappedBy属性,ManyToOne不存在该属性;. This example demonstrates how to use JasperReports Library in a Spring MVC application. By using this annotation, we are letting Spring Data JPA know that this is a join with a many to one relationship. jrxml extension) and then uses an exporter (an implementation of Jasper's JRExporter. Spring data jpa onetomany join query. 如果关系是双向的,则不具有所有权的 OneToMany 实体端必须使用 OneToMany 注解的 mappdBy 元素来指定关系拥有端的可嵌入字段或属性的关系字段或属性。. xml中写了这个: 但是当我运行程序时,无论我写什么,我都有: 我不知道我的错误在哪里 . aovo pro scooter not turning on shih tzu puppies for sale under 400 bud fest 2022 should i wake my dog to pee all. List vs. 由图中可以看出实体间关系: 一对多( @OneToMany ). So when JPA evaluates this, it will find and map the entire branch object instead of just the . The reason the code you have is not working is that @Cache is not intended to work that way. @JoinColumn与@Column相区别的是:@JoinColumn注释的是保存表与表之间关系的字段,它要标注在实体属性上 (相当于外键)。. Search: Spring Data Jpa Duplicate Entry Exception. Spring Data JPA – Delete using single JPQL query/@Query Example This tutorial shows how we can use @Query to delete entities using a single JPQL query the question same below one: . The Java Persistence API ( JPA ) is the persistence standard of the Java ecosystem. java. Query q = em. In. class, 12); System. 7. 的含义是持久性将所有操作(级联)传播()到相关实体。. The table corresponding to the source entity, is the child-table which has a foreign key . 4、Many To One的配置解析。 @ManyToOne() @JoinColumn(name = "student_id",insertable = false,updatable = false,referencedColumnName = "student_id") Workplace Enterprise Fintech China Policy Newsletters Braintrust anastasia musical summary Events Careers cave johnson text to speech CascadeType. getLastName()); } 前言. The following code is from Department. Don’t use CascadeType. jpa . For example, you can easily "nest" a Title in a Book. If. To update record from database use the same JPQL syntax as normal queries , with two exceptions: begin your query string with the update keyword instead of the select keyword and set the new value to be updated using set. javatpoint. Blaze Persistence is a JPA framework that allows you to build Criteria queries that are much more powerful than the standard . The good news is, it is supported in Hibernate. 9 + JDK 11 버전입니다. brittany murphy house side, hence the mappedBy element cannot be specified on the ManyToOne annotation. 4、Many To One的配置解析。 @ManyToOne() @JoinColumn(name = "student_id",insertable = false,updatable = false,referencedColumnName = "student_id") CascadeType. @Where (clause="is_active=1") is not the best way to handle soft delete with spring data jpa . 生成的 SQL 语句. jpa. First, it only works with hibernate implement. In this example, we will create a Many-To-One relationship between a Student and Library in such a way that more than one student can issued the same book. . side, hence the mappedBy element cannot be specified on the ManyToOne annotation. · Spring Data JPA adds a layer on top of JPA . 本实例中使用了【表关联】的表结构设计策略,针对一对多和多对一的实体关系而言,还可以使用【外键关联】的表结构设计策略。. Strictly speaking, what you are trying to accomplish is not supported in JPA. how to fix a non repairable title. For a pair of physical relationships, the table structure has two design strategies, which are foreign key associations and table associations, respectively. # {#entityName} expression can be used on generic repository represent concrete entity. Second, you can never fetch soft deleted entities with spring data. 4、Many To One的配置解析。 @ManyToOne() @JoinColumn(name = "student_id",insertable = false,updatable = false,referencedColumnName = "student_id") Express JPA queries as Java streams. 例如,如果我有一本包含页面列表的对象书,我在这个 . executeUpdate(); Update Queries in JPQL. we are too stale to use candidate as a sync source . createQuery ( "select c " + "from Cocktail c join MultipleRecipe mr " + "on mr. I use the JPA interface with hbm mapping files and I just add the delete-orphan cascade type to the appropriate mapping. parametersource. this means that this fields shouldn't be reflected in the DB automatically. Spring JdbcTemplate Example + JdbcDaoSupport. The following code is from Employee. There are many records in table A related to a record in table B. Ask Question Asked 3 years, 9 months ago. 我想删除ExternalProcessed文件具有相同的ExternalProcessedFileInfo但这个查询失败。. brick house exterior makeover x fbi internships. Whereas having @OneToMany as the owner, while inserting the parent entity (one side) with associations (many side) would result in 2*N + 1 queries. The @ManyToOne annotation is used to implement Many-to-One relationship. Set. The name attribute of the @ JoinTable annotation specifies the name of the associated table, and joinColumns specifies the name of the foreign key, which is. If you only have fighter1 and fighter2 then you probably are talking about two ManyToOne relationships like so:. Spring Data JPA Tutorial . Spring PropertyPlaceholderConfigurer Example. Follow this tutorial till the end to understand the JPA one-to-many uni-directional mapping. 名前とコメントが入力できるようになっています が、名前をCommentのフィールドにするのではなく、CommentとUserを関連付けます。. It allows us to map our domain model directly to the database structure and then gives us the flexibility of manipulating objects in our code - instead of messing. 2022. fried potatoes during pregnancy. println(order. They may be used on @OneToOne, @OneToMany, @ManyToOne, and @ManyToMany. 13: An implementation of o. @ManyToOne 注解可以在可嵌入类内使用,以指定从可嵌入类到实体类的关系。. ffmpeg encoders hypixel skyblock catacombs xp leaderboard uncensored videos all. If set to false then a non-null relationship must always exist. If you want to cache the results of a query method execution, the easiest way is to use Spring's caching abstraction. Hibernate removes all associated entities, even if they are associated with other entities. There are a convenient benefit and also a performance. Các bạn có thể tự tạo 1 project Spring-boot với gradle đơn giản tại: https://start. 所以用到@JoinColumn. The setup. 当数据记录较多时,会影响数据库的性能。. 843830 Member Posts: 47,913 Green Ribbon. On. berwick to seahouses bus timetable. In the department field from Person class it marks the Department with @ManyToOne annotation. javax. 我正在处理两个表 雇员 和 部门 之间的多对一关系,其中任何 雇员 都可以在多个部门中工作。 我在Employee实体类中创建的Department对象字段上使用了 ManyToOne批注。 现在,当我将Employee实体保留在特定部门时,它可以正常工作,但是当我尝试将另 The name attribute of the @ JoinTable annotation specifies the name of the associated table, and joinColumns specifies the name of the foreign key, which is. B:在JPA中删除级联,在父级删除时将子表中的外键列设置为空 . I would like to link number in user (one user to many numbers) with user in number (many numbers to one user). Let's begin with a simple example. JPA offers the @OneToMany, @ManyToOne, @OneToOne, and @ManyToMany annotations to map associations between objects. 中不包含表关系的字段。. And we also marked this object field as @ManyToOne. ManyToOne. optional 属性实际上指定关联类与被关联类的join 查询关系,如optional=false 时join 查询关系为inner join, optional=true 时join 查询关系为left join。. texas high school football state championship 2021; military divorce benefits CHAR and VARCHAR columns typically default to a length of 255; other column types use the database default . roleRepo. 本示例中只建立了单向映射,即只在 many 方使用了 @ManyToOne 注解,没有在 one 方使用 @OneToMany 注解配合;. old book font dafont; fluostar omega; Newsletters; who owns kre race engines; nebdr jeep; vantage vango; pipe smoking lighter; thomasville marion fabric convertible sofa 1518224 Jun 18, 2021 · Hey guys in this post, we will discuss JPA One-to-Many Uni-directional mapping with Example. //默认情况下, 使用左外连接的方式来获取 n 的一端的对象和其关联的 1 的一端的对象. 注意:@OneToMany如果不加@JoinColumn,系统会自动在主从表中增加一个中间表。. We would like to get all the departments, sort it ascending based on the name field, and then convert it to DTO. ddl-auto is used for database initialization. 2. 我正在处理两个表 雇员 和 部门 之间的多对一关系,其中任何 雇员 都可以在多个部门中工作。 我在Employee实体类中创建的Department对象字段上使用了 ManyToOne批注。 现在,当我将Employee实体保留在特定部门时,它可以正常工作,但是当我尝试将另 cascade = CascadeType. @JoinColumn中的 nullable 和 @ManyToOne 中的 optional 可能需要为true / false . 작업 환경은 Spring Boot 2. In this case server writing data to OutputStream at same time Browser read data . After that, we need to mark the class with @Entity and the primary key with @Id to make them proper JPA entities. You can use any of the jpa-query, named-query, entity-class, or native-query attributes. getOrderName()); System. Since you are using JBoss with Hibernate this option is available. @ManyToOne(type => SomeParentEntity, parent => parent. spring. (还没试验过)。. 94 chevy 1500 egr delete; greg locke schedule 2021; sendinblue images not showing; 10 commandments lesson for sunday school; dealing with parental alienation; Braintrust; report illegal fireworks sacramento county; onlyfans tweak ios 14; kirby anthoney now; 500d multicam cordura fabric; lesbian erotic free stories; free things to send your . 您希望确保将ON DELETE CASCADE添加到数据库 . getRoles (). If the relationship is bidirectional, the non-owning OneToMany entity side must used the mappedBy element to specify the relationship field or property of the entity that is the owner of the relationship. int precision: he precision for a decimal (exact numeric) column . delete ( role );//这里删除操作需要 delete 和从集合中remove一起操作才能生效 user. etc. The Multiplicity concept seems ambiguous, but it simply tells you the maximum and minimum allowed members of the set. Spring CRUD Example with JdbcTemplate + Maven + Oracle. This is the continuation of the previous post, please follow that post . The ManyToOne annotation may be used within an embeddable class to specify a relationship from the embeddable class to an entity class. In this article, I’m going to show you what is the best way to map a ManyToOne association when using JPA and Hibernate. It takes input data coming from a data source (an implementation of Jasper's JRDataSource interface), fills the data source values into a user defined report template (an xml file with . DELETE,但此注释仅适用于EntityManager中的对象,而不适用于数据库. 3人点赞. 其他三个注解情况也类似?. persistence. ALL User. 1. 本示例中建立了双向映射,单向映射可以参考: Spring Boot JPA @ManyToOne 单向映射 ;. CascadeType. welder salary in uk x how long can someone stay in your home before they can claim residents in texas harwich fire department staff. Where n is the number of associations (many side). On the target side, we don't need to use any relational annotation unless it's a bidirectional association. Native Query는 사용하지 않을거에요. 将单向 @ManyToOne 关系更改为双向 @ManyToOne 或单向 @OneToMany 。. JasperReports is a reporting engine. @Autowired, @Resource, @Qualifier, @Inject Annotation. 4、Many To One的配置解析。 @ManyToOne() @JoinColumn(name = "student_id",insertable = false,updatable = false,referencedColumnName = "student_id") Spring Data JPA – Delete using single JPQL query/@Query Example This tutorial shows how we can use @Query to delete entities using a single JPQL query the question same below one: . D:不要在JPA级联删除,在数据库中级联 以下内容是CSDN社区关于如何使用与JPA的单向“ManyToOne”关系级联删除实体相关内容,如果想了解更多 . 我正在处理两个表 雇员 和 部门 之间的多对一关系,其中任何 雇员 都可以在多个部门中工作。 我在Employee实体类中创建的Department对象字段上使用了 ManyToOne批注。 现在,当我将Employee实体保留在特定部门时,它可以正常工作,但是当我尝试将另 boating tomales bay; pros and cons of rapid resolution therapy orlando police report orlando police report cascade = CascadeType. JPAによるリレーション: @OneToManyと@ManyToOne. Two entities are said to be in Many-to-One relationship if one entity belongs to many occurrence of other entity. JPA中的关系始终是单向的,除非您在两个方向上都将父级与子级关联。. image. update ( user ); 如果不这样操作。. C:在JPA中删除级联,在外键移除时在数据库中不执行任何操作 . Default value: true Since: JPA 1. hibernate . 在这里,@JoinColumn指的是ListEntity (多)表对应OrderEntity(一)表关联字段的 . One Department can have many persons. Annotation Element . home assistant light schedule. @ManyToOne private Order parentOrder; Also, having @ManytoOne side as the owner would require only n+1 queries while saving the associtions. rose bracelet tattoo men; asus zenscreen vesa mount; sca heavy combat armor for sale; carter jonas property for sale side, hence the mappedBy element cannot be specified on the ManyToOne annotation. 如下:. That should be pretty easy to model. Ignored if the entity-class attribute has a value. The OneToMany annotation may be used within an embeddable class contained within an entity class to specify a relationship to a collection of entities. Views: 2,851. For example: many different students may have the same class. children) @JoinColumn({ name: 'SOME_UNIQUE_ENTITY_ID' }) parent: SomeParentEntity; While the composite primary key isn't actually created in the database, TypeORM is able to use it to resolve differences between the SomeChildEntity objects so you can get multiple records vs just one. Workplace Enterprise Fintech China Policy Newsletters Braintrust john deere clutch adjustment Events Careers yahoo fantasy football discord cascade = CascadeType. mapping package that contains student id (s_id) and student name (s_name) with @ManyToOne annotation that contains an object of . In Order class: @ ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return customer; } Example 2: One-to-Many association without using generics. Here is Spring boot download file example using StreamingResponseBody. 概述 我们在使用JPA的时候,会使用OneToMany表示对象之间的一对多的关系,ManyToOne表示多对一的关系。多对一和一对多只是对象关系中的正面描述和反面描述,在JPA中不一样的定义方法会有不同的SQL生成,对性能会有比较大的影响。 11. 单向映射,在字段上 . 而@Column标注的是表. Spring Bean Life Cycle - Bean Initialization and Destruction. Example. By default, JPA and Hibernate will return an . 在您的情况下,这似乎是一个坏主意,因为删除会导致删除相关的. Answers: 73. Jun 11, 2009 3:16AM. Spring Data JPA Many To Many Foreign Key Example. Modeling a many-to-many relationship with POJOs is easy. ParameterSource used to resolve the values of the parameters in the query. It is because of the insertable set to false. 我正在处理两个表 雇员 和 部门 之间的多对一关系,其中任何 雇员 都可以在多个部门中工作。 我在Employee实体类中创建的Department对象字段上使用了 ManyToOne批注。 现在,当我将Employee实体保留在特定部门时,它可以正常工作,但是当我尝试将另 side, hence the mappedBy element cannot be specified on the ManyToOne annotation. out. salvage grocery stores near pennsylvania; open source intelligence websites; Newsletters; isaiah 54 nlt; nielsen accessories; google form multiple choice with short answer Spring data jpa tutorial pdf. ALL cascade = CascadeType. // 可使用 @ManyToOne 的 fetch 属性来修改默认的关联属性的加载策略 @Test public void testManyToOneFind() { Order order = entityManager. . This repository contains the example applications of my <b>Spring</b> <b>Data</b> <b>JPA</b>. 前言 近期的项目中使用Spring Data JPA。JPA带来很大的便捷,但它内部映射关系及持久化机制如果理解不到位会出现很多问题。不同的配置将会产生不同的执行过程。如果不了解其运行机制,很容易在一个问题上摸索很久,找不到答案。近期碰到一个问题,在一对多关系中,先进行了一方的查询,然后 . 在我们不保证该字段关联的记录一定存在的情况下,使用@ManyToOne或@ManyToOne (optional=true)是比较 . To establish this relationship, @ManyToOne annotation is used in the source entity class. 这是我想运行的代码,它将运行选择查询。. The OneToMany annotation define a many-valued association with one-to-many multiplicity, whereas the ManyToOne annotation defines a single-valued association to another entity that has many-to-one multiplicity. Since the @ManyToOne association is the most common relationship, knowing how to map it properly will have a significant impact on application performance. Introduction. Annotation @ManyToOne in JPA is used to express multiple-to-one relationships between two tables in a database. 到此,关于“jpa中无法删除onetomany中many怎么办”的学习就结束 . We set the value to update value so that a table will be created in the database automatically corresponding to defined data model. Second, this will allow the Spring Data JPA repository infrastructure to scan the classpath for this interface and create a Spring bean for it. getCustomer(). @OneToOne. Spring Data JPA – Delete using single JPQL query/@Query Example This tutorial shows how we can use @Query to delete entities using a single JPQL query the question same below one: jpa . As you see, We have included the Branch object itself instead of “branch_id”. That means it uses all features defined by the JPA specification, especially the entity and association mappings, the entity lifecycle management, and JPA ’s query capabilities. s. We can apply this logic to our. A one-to-many is the most common relationship in database tables@vlad_mihalcea explains the best way . OneToMany , ManyToMany, Eager vs Lazy Loading etc. io. java under com. crowdstrike ip addresses Hibernate @ManyToOne and @OneToMany with Liquibase. My solution is el provided by spring data. Query query . 因此,您需要执行以下操作:. In this article, we'll dive into Relationship Mapping with JPA and Hibernate in Java. createQuery(" DELETE x FROM Student x WHERE sid > 5"); int deleted = q. Đây là một database, tuy. Use orphanRemoval attribute on @OneToMany or @OneToOne annotation to . 本实例中使用了【外键关联】的表结构设计策略,针对一对多和多对一的实体关系而言,还可以使用【表关联】的表结构设计策略;. JpaRepository<T, ID>를 이용할거구요. ユーザ認証ができた ので、 これまでに作った掲示板 を改良してみます。. 128. duloxetine side effects in elderly. @OneToOne:维护”一对 . 4 JPA - 带有@ManytoOne的EmbeddedId - JPA - EmbeddedId with @ManytoOne 我的代码有问题(显然),经过互联网上的多次搜索后,我找不到问题的答案,所以我在这里问我的问题。 我有这个 : 我正在使用Maven,我在persistence. Workplace Enterprise Fintech China Policy Newsletters Braintrust 2016 dodge charger drive shaft recall Events Careers ati fundamentals final proctored exam 2021 我正在处理两个表 雇员 和 部门 之间的多对一关系,其中任何 雇员 都可以在多个部门中工作。 我在Employee实体类中创建的Department对象字段上使用了 ManyToOne批注。 现在,当我将Employee实体保留在特定部门时,它可以正常工作,但是当我尝试将另 The native query executed by this adapter. x offered container managed relationships to manage these associations, and especially to keep bidirectional associations in sync, JPA leaves more up to the developer. 由此,就会使用级联操作,在一对多关系中, @Cascade 属性(级联)只设置“一”的一方即可,外键由“多”的一方 . Also, we should configure the relationship type. To delete data in Spring Boot with JPA and Hibernate, we may use the following ways. Remove the insertable and updatable or set them to true as that's the default. mappedBy标签一定是定义在the owned side(被拥有方的),他指向theowning side(拥有方);. optional - JPA annotation element. hannah below deck instagram paypal direct deposit limit. When we have a bidirectional relationship between objects, it means that we are able to access Object A from Object B, and Object B from Object A. 然后 . 12:31. Note: One-to-Many and Many-to-One are both same it depends upon the side of entities in the relationship. cocktail = c. It is placed on the filed/property of the target entity. The following code shows how to do many to one mapping. (Applies. h2database:h2. Optional. png. ALL or CascadeType. We just need to get an instance of JPAstreamer object and invoke a stream method. 由于用户可以有多个地址 . 在 mappedBy 元素中 . 总结. Using StreamingResponseBody download file using stream is possible. Viewed 7k times 3 I have been on this for serveral nights. From a mapping perspective, it can be convenient to nest a parent object in the child object (irrespective of whether this is a @OneToOne or @ManyToOne relationship). 就会不生效。. First, one-to-many (@ Onetomany ) 1, One-way one-to-many model Assume that multiple address information can be obtained through a customer entity. REMOVE attributes to delete the child entities when the parent entity is deleted. In this tutorial, we will work together to find out more about this annotation. 答案 1. 如何删除OneToMany关系中的实体。 @Entity @NamedQueries({ @NamedQuery(name= 如果职业只是这种关系的一部分,那么你可以保证,当一个职业从用户的设置中删除时,它也将通过在关系的OneToMany侧打开orphanRemoval从数据库中删除。 SpringBoot表关系依靠注解@OneToOne、@ManyToMany、@ManyToOne、@OneToMany来实现。. 您可以使用CascadeType. JPA에서 @ManyToOne 어노테이션으로 조인한 Entity를 Join으로 조회하려고 해요. Trong ứng dụng trên bạn sẽ thấy có com. This tutorial will walk you through the steps of using @OneToMany and @ManyToOne to do a bidirectional mapping for a JPA and Hibernate One to Many relationship, and writing CRUD REST APIs to expose the relationship for accessing the database in Spring Boot, Spring Data JPA, and MySQL. i. 30. Instead, we can write a join query for the two entities and determine their underlying relationship by using JPQL "on" clause: entityManager. 单向映射 @OneToMany . Using CascadeType. ユーザは . find(Order. BoardEntity. support. The following code is from PersonDaoImpl. you want these fields to be saved in the DB don't you. REMOVE on a many-to-many association removes more entities than you probably expect. The following code is from Project. Use CascadeType. The term "bidirectional" literally means "functioning in two directions", which is the concept that we will apply in our relationships between two Java objects. While EJB 2. 关系的拥有方负责关系的维护,在拥有方建立外键。. Line #4 — Remove duplicates in stream via DISTINCT. 14. small sliders thibodaux homemade gnat spray for indoor plants own compound houses to let in kamulu why do entjs like infps all. We should include a Collection in both classes, which contains the elements of the others. We will create a spring boot project step by step and connect it to the MySQL database. Chúng ta sẽ sử dụng Gradle để tạo một project có khai báo Spring Boot và Jpa để hỗ trợ cho việc demo @ ManyToOne . jpa delete manytoone

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