BAEL-2811: Added sample code for jpa joins (#6691)

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/joins/model/Department.java

@@ -0,0 +1,45 @@
+package com.baeldung.joins.model;
+
+import java.util.List;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+
+@Entity
+public class Department {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private long id;
+
+    private String name;
+
+    @OneToMany(mappedBy = "department")
+    private List<Employee> employees;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<Employee> getEmployees() {
+        return employees;
+    }
+
+    public void setEmployees(List<Employee> employees) {
+        this.employees = employees;
+    }
+}

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/joins/model/Employee.java

@@ -0,0 +1,69 @@
+package com.baeldung.joins.model;
+
+import java.util.List;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.ManyToOne;
+import javax.persistence.OneToMany;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "joins_employee")
+public class Employee {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private long id;
+
+    private String name;
+
+    private int age;
+
+    @ManyToOne
+    private Department department;
+
+    @OneToMany(mappedBy = "employee")
+    private List<Phone> phones;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public Department getDepartment() {
+        return department;
+    }
+
+    public void setDepartment(Department department) {
+        this.department = department;
+    }
+
+    public List<Phone> getPhones() {
+        return phones;
+    }
+
+    public void setPhones(List<Phone> phones) {
+        this.phones = phones;
+    }
+}

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/joins/model/Phone.java

@@ -0,0 +1,44 @@
+package com.baeldung.joins.model;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.ManyToOne;
+
+@Entity
+public class Phone {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private long id;
+
+    private String number;
+
+    @ManyToOne
+    private Employee employee;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getNumber() {
+        return number;
+    }
+
+    public void setNumber(String number) {
+        this.number = number;
+    }
+
+    public Employee getEmployee() {
+        return employee;
+    }
+
+    public void setEmployee(Employee employee) {
+        this.employee = employee;
+    }
+}

persistence-modules/spring-data-jpa-2/src/main/resources/application-joins.properties

@@ -0,0 +1 @@
+spring.datasource.data=classpath:db/import_joins.sql

persistence-modules/spring-data-jpa-2/src/main/resources/db/import_joins.sql

@@ -0,0 +1,13 @@
+INSERT INTO department (id, name) VALUES (1, 'Infra');
+INSERT INTO department (id, name) VALUES (2, 'Accounting');
+INSERT INTO department (id, name) VALUES (3, 'Management');
+
+INSERT INTO joins_employee (id, name, age, department_id) VALUES (1, 'Baeldung', '35', 1);
+INSERT INTO joins_employee (id, name, age, department_id) VALUES (2, 'John', '35', 2);
+INSERT INTO joins_employee (id, name, age, department_id) VALUES (3, 'Jane', '35', 2);
+
+INSERT INTO phone (id, number, employee_id) VALUES (1, '111', 1);
+INSERT INTO phone (id, number, employee_id) VALUES (2, '222', 1);
+INSERT INTO phone (id, number, employee_id) VALUES (3, '333', 1);
+
+COMMIT;