hql

问题 I have a table containing over 50 columns (both numeric and char), is there a way to get the overall statistics without specifying each column? As an example: a b c d 1 2 3 4 5 6 7 8 9 10 11 12 Ideally I would have something like: column_name min avg max sum a 1 5 9 15 b 2 6 10 18 c 3 7 11 21 d 4 8 12 24 Nevertheless, getting one aggregate at a time it would be more more than helpful. Any help/idea would be highly appreciated. Thank you, O 回答1: You can parse DESCRIBE TABLE output using AWK

问题 It was a while since a worked with ORM on Java and currently looking for an option prevent recursive references in OneToMany-like relationships. Here is trivial sample. @Entity public class InnerEntity extends BaseEntity { private String name; @ManyToOne(fetch = FetchType.LAZY) private OuterEntity host; public InnerEntity() { } public InnerEntity(String name, OuterEntity host) { this.name = name; this.host = host; } public String getName() { return name; } public void setName(String name) {

问题 I have a table with two columns: id, datastring The id column is just a bigint and the datastring column has elements that look like {"12345":[6789,true]} {"1234678":[5678, false]} I would like to select a table where the first column is the id and the second column is the number in the quotes part of the datastring. However, this number is not always the same number of digits. The result should be id, numstring 4321, 12345 4322, 134678 Thanks in advance. 回答1: You have at least two options.

问题 Im working on a java standAlone project. I need to use hibernate in a MultiThread application but i just cant figure it out how to set up this correctly. Each Thread deals with the same process of the others. Everything goes Ok when i run it in a Non-Async way, but when i call the same thing using threads, hibernate just don't work fine. Can anyone please explain me what's the correct way to use Hibernate in a multiThread Java Stand-Alone App? Hibernate Util public class HibernateUtil {

问题 Im working on a java standAlone project. I need to use hibernate in a MultiThread application but i just cant figure it out how to set up this correctly. Each Thread deals with the same process of the others. Everything goes Ok when i run it in a Non-Async way, but when i call the same thing using threads, hibernate just don't work fine. Can anyone please explain me what's the correct way to use Hibernate in a multiThread Java Stand-Alone App? Hibernate Util public class HibernateUtil {

问题 Entity Project has a collection property contributors mapped with a @OneToMany relationship to entity User @Entity @Table( name = "projects" ) public class Project { ... @OneToMany @JoinTable(name = "project_contributors") private List<User> contributors = new ArrayList<User>(); ... } I then need to check if contributors already has a user with id contributorId before adding it. I am trying with HQL query, but I am clearly quite innept. What I am trying: Query query = session.createQuery(

问题 I have entity like this: @Getter @Setter @Entity public class Conversation extends AbstractEntity{ @ElementCollection @Column(name = "user_id", nullable = false) @CollectionTable(name = "conversation_user", joinColumns = @JoinColumn(name = "conversation_id", nullable = false)) private List<String> usersIds; } Is possible to find conversation entity by spring's repository by exact matching of user ids? For instance I have these entities: id | user_ids ------------------------------------------

问题 I would like to clarify some points regarding the secondary level cache of hibernate. The point to clarify is, will the HQL queries always hit the database (at least for getting ids). Consider we have entities class Customer { long id; // Primary key String name; set <Address> addressList; // One to many relationship } class Address{ long id; // Primary key String houseName; } The database table for the Address has a foreign key reference to the Customer (id) to support one to many

问题 I would like to clarify some points regarding the secondary level cache of hibernate. The point to clarify is, will the HQL queries always hit the database (at least for getting ids). Consider we have entities class Customer { long id; // Primary key String name; set <Address> addressList; // One to many relationship } class Address{ long id; // Primary key String houseName; } The database table for the Address has a foreign key reference to the Customer (id) to support one to many

问题 In spring boot app I have an ElementEntity: .... @Entity public class ElementEntity { @Id int id; Double quantity; String form; String color; String type; String description; @ManyToOne @JoinColumn(name = "form") private FormEntity form; } And I have here FormEntity: @Entity public class FormEntity { ..... @OneToMany @JoinColumn(name = "links") private List<LinksEntity> links; } I want using HQL to generate a query that will sum the values of quantity field, group by color and and to return