Mapping EXCEL Sheet to Database using JPA Hibernate - mysql

Question

I would like to map an simple excel table to my javaEE application using hibernate. I'm really new to Databases and ORM so i would like to know if the following relations make sense and in how many Entities would make sense to split the Table.
This is the attributes contained in the Excel spreadsheet:
(Office Room Number|ComputerName|ComputerIP|Computer OS|UserFirstName|UserLastName)
Relations:
OfficeRoomNumber -- 1 : N -- Users
N users working in 1 Office?
OfficeRoomNumber -- 1 : N -- Computer
N Computers are in 1 Office ?
User -- 1:1 -- Computer
1 User got 1 Computer?
Thanks for any help and sorry for my horrible English.

Answer 1

Here are my 50c for modelling your domain. First, one can use an abstract base class for generic aspects, such as primary key generation:
#MappedSuperClass
public abstract class AbstractEntity {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "pk-sequence")
#SequenceGenerator(name = "pk-sequence", sequenceName = "ID_GEN", allocationSize = 1)
protected Long objectID = -1;
#Version
private int version;
public int getVersion() {
return version;
}
public long getObjectID() {
return objectID;
}
}
Note well, this can be enhanced to include other generic aspects, e.g. creation/modification date/timestamps.
Next, we introduce three domain classes/entities as follows:
#Entity
public class OfficeRoom extends AbstractEntity {
private String name;
private String roomNumer;
#ManyToMany // Maybe an employee is associated with 2 or more office places she/he might work at?
private Collection<Employee> staff;
#OneToMany(mappedBy="location")
private Collection<Computer> equipment;
// getters and setters
}
I added a comment as you can see above on the field staff. Potentially, one would like to associated two different office rooms to certain VIP staff, so you should consider this case in modelling your domain by using #ManyToMany here already.
Moving on with:
#Entity
public class Computer extends AbstractEntity {
private String name;
private String model;
private String vendor;
private String installedOS;
private String ipAddress;
#ManyToOne
private OfficeRoom location;
#OneToMany(mappedBy="machine") // Maybe a computer is associated with 2 or more employees?
private Collection<Employee> user;
// getters and setters
}
Again, consider my comment carefully. Finally,...
#Entity
public class Employee extends AbstractEntity {
private String firstName;
private String lastName;
// other staff related attributes here ...
#ManyToOne
private Computer machine;
// getters and setters
}
Note well: Use only annotations originating from the javax.persistence package, in your import statements to stay compliant with the JPA 2.x specification and remain JPA-provider neutral with your application.
Hope this helps.