hibernate

问题 What is the difference between these two Automatic value generation strategies? 1. @GeneratedValue 2. @GeneratedValue(strategy=IDENTITY) 回答1: This is like following: AUTO Indicates that the persistence provider should pick an appropriate strategy for the particular database. IDENTITY Indicates that the persistence provider must assign primary keys for the entity using database identity column. SEQUENCE Indicates that the persistence provider must assign primary keys for the entity using

问题 What is the difference between these two Automatic value generation strategies? 1. @GeneratedValue 2. @GeneratedValue(strategy=IDENTITY) 回答1: This is like following: AUTO Indicates that the persistence provider should pick an appropriate strategy for the particular database. IDENTITY Indicates that the persistence provider must assign primary keys for the entity using database identity column. SEQUENCE Indicates that the persistence provider must assign primary keys for the entity using

问题 Okay, I'm trying to do something quite strange. I'm trying to use CriteriaBuilder and CriteriaQuery to return all entities who contain a given object in a collection on the entity. I've been banging my head against this for hours and the relevant documentation is little and not particularly useful. Any help would be greatly appreciated. Relevant excerpts of the classes are as follows. @Entity public class Entry { @ManyToMany(fetch=FetchType.EAGER) private List<Tag> tags = new ArrayList<Tag>()

问题 Okay, I'm trying to do something quite strange. I'm trying to use CriteriaBuilder and CriteriaQuery to return all entities who contain a given object in a collection on the entity. I've been banging my head against this for hours and the relevant documentation is little and not particularly useful. Any help would be greatly appreciated. Relevant excerpts of the classes are as follows. @Entity public class Entry { @ManyToMany(fetch=FetchType.EAGER) private List<Tag> tags = new ArrayList<Tag>()

问题 Okay, I'm trying to do something quite strange. I'm trying to use CriteriaBuilder and CriteriaQuery to return all entities who contain a given object in a collection on the entity. I've been banging my head against this for hours and the relevant documentation is little and not particularly useful. Any help would be greatly appreciated. Relevant excerpts of the classes are as follows. @Entity public class Entry { @ManyToMany(fetch=FetchType.EAGER) private List<Tag> tags = new ArrayList<Tag>()

问题 I have a table with lot of fields such as Account OrderNo Term LegNo LegSymbol LegSymbolType LegExchangeType etc etc The primary key of the above table is a composite key comprising of Account, OrderNo & LegNo The data in the DB would look something like this 1234 1 2 1 AAA BBB CCC 1234 1 2 2 DDD EEE FFF The bolded ones are Account,Order,LegNo respectively. While designing the entity for the above table, we want to group all the Leg related information (All bolded columns ) in a separate

问题 I'm trying to implement One-to-Many relation between two tables using hibernate. Here is my code: @Entity public class Board { @Id @Column(name = "board_id") @GeneratedValue private long id; @Column private String owner; @Column private String title; @Column private String refresh; @Column private Timestamp createDate; @Column private Timestamp modifyDate; @OneToMany(mappedBy="board", cascade=CascadeType.ALL) private List<Item> items; public long getId() { return id; } public void setId(long

问题 I'm trying to implement One-to-Many relation between two tables using hibernate. Here is my code: @Entity public class Board { @Id @Column(name = "board_id") @GeneratedValue private long id; @Column private String owner; @Column private String title; @Column private String refresh; @Column private Timestamp createDate; @Column private Timestamp modifyDate; @OneToMany(mappedBy="board", cascade=CascadeType.ALL) private List<Item> items; public long getId() { return id; } public void setId(long

问题 Been trying hard to search for a solution to create some Custom JPA Annotations to replace repetitive fields when declaring Entity POJOs. Any help? Here what I am trying to achieve: //@Column(name = "is_enabled", nullable = false, columnDefinition = "tinyint(1) DEFAULT 1") @ColumnBooleanNotNullDefaultOne private Boolean isEnabled; or //@Column(name = "created", nullable = false, updatable = false, insertable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP") @ColumnTimestamp

问题 Hello I'm using the following hibernate-core-4.1.2.Final.jar mysql-connector-5.1.6.jar Both can be found in my project lib directory. I have the following hibernate.cg.xml configuration. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- Defines the SQL dialect used in Hiberante's application -->