怎么申请免费国内免费网站,WordPress文章付费系统,汉服网站设计目的,做网站后台的时候要注意什么hibernate 别名如果在复杂查询的情况下使用Hibernate模式#xff0c;则需要使用sql。 因此#xff0c;sqlRestrictions可以解决。 但是#xff0c;对联接表别名使用sql限制有点棘手。 将有三个表#xff1a; 公司表。 员工表。 每个员工都属于一个公司#xff0c;因此… hibernate 别名 如果在复杂查询的情况下使用Hibernate模式则需要使用sql。 因此sqlRestrictions可以解决。 但是对联接表别名使用sql限制有点棘手。 将有三个表 公司表。 员工表。 每个员工都属于一个公司因此我们有多对一的关系。 福利表。 每个公司都有很多好处因此我们有一对多的关系。 本示例将使用Postgresql。 CREATE DATABASE example;CREATE TABLE company (company_id SERIAL PRIMARY KEY,name TEXT NOT NULL
);CREATE TABLE employee (employee_id SERIAL PRIMARY KEY,first_name TEXT,last_name TEXT,company_id integer,CONSTRAINT fk_company FOREIGN KEY (company_id)REFERENCES company (company_id) MATCH SIMPLE
);CREATE TABLE benefit (benefit_id SERIAL PRIMARY KEY,name TEXT,company_id integer,CONSTRAINT fk_company FOREIGN KEY (company_id)REFERENCES company (company_id) MATCH SIMPLE
);INSERT INTO company (name) VALUES (TestCompany);
INSERT INTO employee (first_name, last_name, company_id) VALUES (Emmanouil,Gkatziouras,1);
INSERT INTO benefit (name,company_id) VALUES (gym,1); JPA将用于实体配置。 公司实体。 package com.gkatzioura.example.entity;import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;/*** Created by gkatziourasemmanouil on 7/12/15.*/
Entity
Table(name company)
public class Company {IdGeneratedValueColumn(name company_id)private Long Id;ColumnString name;OneToMany(cascade CascadeType.ALL,fetch FetchType.LAZY,mappedBy company)private SetBenefit benefits new HashSetBenefit();public Long getId() {return Id;}public void setId(Long id) {Id id;}public String getName() {return name;}public void setName(String name) {this.name name;}public SetBenefit getBenefits() {return benefits;}public void setBenefits(SetBenefit benefits) {this.benefits benefits;}
} 员工实体。 package com.gkatzioura.example.entity;import javax.persistence.*;/*** Created by gkatziourasemmanouil on 8/2/15.*/
Entity
Table(name employee)
public class Employee {IdGeneratedValueColumn(name employee_id)private Long id;Column(name first_name)private String firstName;Column(name last_name)private String lastName;ManyToOne(cascade CascadeType.ALL,fetch FetchType.LAZY)JoinColumn(name company_id,referencedColumnName company_id)private Company company;public Long getId() {return id;}public void setId(Long id) {this.id id;}public Company getCompany() {return company;}public void setCompany(Company company) {this.company company;}public String getLastName() {return lastName;}public void setLastName(String lastName) {this.lastName lastName;}public String getFirstName() {return firstName;}public void setFirstName(String firstName) {this.firstName firstName;}
} 利益实体。 package com.gkatzioura.example.entity;import javax.persistence.*;/*** Created by gkatziourasemmanouil on 8/9/15.*/Entity
Table(name benefit)
public class Benefit {IdGeneratedValueColumn(name benefit_id)private Long id;Column(name name)private String name;ManyToOneJoinColumn(name company_id)private Company company;public String getName() {return name;}public void setName(String name) {this.name name;}public Long getId() {return id;}public void setId(Long id) {this.id id;}public Company getCompany() {return company;}public void setCompany(Company company) {this.company company;}
} Hibernate配置 ?xml version1.0 encodingutf-8?
!DOCTYPE hibernate-configuration PUBLIC-//Hibernate/Hibernate Configuration DTD 3.0//ENhttp://hibernate.sourceforge.net/hibernate-configuration-3.0.dtdhibernate-configurationsession-factory!-- Database connection settings --property nameconnection.driver_classorg.postgresql.Driver/propertyproperty nameconnection.urljdbc:postgresql://127.0.0.1:5432/example/propertyproperty nameconnection.usernamepostgres/propertyproperty nameconnection.passwordpostgres/property!-- JDBC connection pool (use the built-in) --property nameconnection.pool_size1/property!-- SQL dialect --property namedialectorg.hibernate.dialect.PostgreSQL9Dialect/property!-- Enable Hibernates automatic session context management --property namecurrent_session_context_classthread/property!-- Disable the second-level cache --property namecache.provider_classorg.hibernate.cache.NoCacheProvider/property!-- Echo all executed SQL to stdout --property nameshow_sqltrue/property!-- Drop and re-create the database schema on startup --property namehbm2ddl.autoupdate/propertymapping classcom.gkatzioura.example.entity.Company/mapping classcom.gkatzioura.example.entity.Employee/mapping classcom.gkatzioura.example.entity.Benefit//session-factory/hibernate-configuration 创建Hibernate会话工厂的主类 package com.gkatzioura.example;import com.gkatzioura.example.entity.Employee;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;
import org.hibernate.sql.JoinType;
import org.hibernate.type.StringType;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;/*** Created by gkatziourasemmanouil on 7/12/15.*/
public class Main {private static SessionFactory sessionFactory;private static final org.slf4j.Logger LOGGER LoggerFactory.getLogger(SessionFactory.class);public static void main(String args[]) {sessionFactory buildSessionFactory();getByCompanyAndBenefit(TestCompany,gym);sessionFactory.close();}public static SessionFactory buildSessionFactory() {return new Configuration().configure().buildSessionFactory();}} 假设我们要通过公司名称和特定的福利名称来提取员工我们将添加getByCompanyAndBenefit函数。 公司名称将通过常规限制进行过滤。 但是福利名称将由sqlRestriction过滤。 private static ListEmployee getByCompanyAndBenefit(String companyName,String benefitName) {Session session sessionFactory.openSession();Criteria criteria session.createCriteria(Employee.class,employee);Criteria companyCriteria criteria.createCriteria(company,JoinType.INNER_JOIN);companyCriteria.add(Restrictions.eq(name, companyName));Criteria benefitsAlias companyCriteria.createCriteria(benefits,JoinType.LEFT_OUTER_JOIN);benefitsAlias.add(Restrictions.sqlRestriction({alias}.name ?,benefitName, StringType.INSTANCE));ListEmployee employees criteria.list();for(Employee employee:employees) {LOGGER.error(The employee is employee.getFirstName());}session.close();return employees;} 对关系使用条件的createCriteria函数时{alias}表示新条件的关联实体。 对于使用createAlias之后检索到的条件类这是不可能的。 最后但并非最不重要的gradle文件。 group com.gkatzioura.example
version 1.0-SNAPSHOTapply plugin: application
apply plugin: java
apply plugin: ideamainClassName com.gkatzioura.example.MainsourceCompatibility 1.8repositories {mavenLocal()mavenCentral()
}dependencies {testCompile group: junit, name: junit, version: 4.11compile org.ancoron.postgresql:org.postgresql.net:9.1.901.jdbc4.1-rc9compile org.slf4j:slf4j-api:1.6.6compile ch.qos.logback:logback-classic:1.0.13compile org.hibernate:hibernate-core:4.3.6.Finalcompile org.hibernate:hibernate-entitymanager:4.3.6.Finalcompile org.hibernate:hibernate-validator:5.1.1.Finalcompile dom4j:dom4j:1.6.1compile org.hibernate.javax.persistence:hibernate-jpa-2.1-api:1.0.0.FinaltestCompile group: junit, name: junit, version:3.8.1}翻译自: https://www.javacodegeeks.com/2015/08/hibernate-use-join-table-alias-on-sqlrestriction.htmlhibernate 别名
