hibernate how to deal with divided to many tables

Question

i use hibernate deal with entity. the classes are

@Entity
@Table(name="bus_line")
@NamedQuery(name="BusLine.findAll", query="SELECT b FROM BusLine b")
public class BusLine implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(unique=true, nullable=false)
    private Long id;

    @Column(nullable=false)
    private Long firstExpressTime;

    @Column(nullable=false)
    private Long lastExpressTime;

    private Integer lineDirection;

    @Column(nullable=false, length=10)
    private String lineName;

    @Column(nullable=false)
    private Long originatingStationID;

    @Column(nullable=false, length=10)
    private String originatingStationName;

    @Column(nullable=false)
    private Long terminusID;

    @Column(nullable=false, length=10)
    private String terminusName;

    @ManyToMany(mappedBy="busLines")
    private List<BusStation> busStations = new ArrayList<BusStation>();
    omit getter and setter method
}

@Entity
@Table(name="bus_station")
@NamedQuery(name="BusStation.findAll", query="SELECT b FROM BusStation b")
public class BusStation implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(unique=true, nullable=false)
    private Long id;

    @Column(nullable=false)
    private Double stationLat;

    @Column(nullable=false)
    private Double stationLng;

    @Column(nullable=false, length=20)
    private String stationName;

    @JoinTable(name="bus_line_to_station",joinColumns = @JoinColumn(name="stationID"),
            inverseJoinColumns=@JoinColumn(name="lineID"))
    private List<BusLine> busLines = new ArrayList<BusLine>();

    omit setter and getter method
}

the table is

   CREATE TABLE `bus_line` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT ,
  `lineName` varchar(10) NOT NULL ,
  `originatingStationName` varchar(10) NOT NULL ,
  `originatingStationID` bigint(20) NOT NULL ,
  `terminusID` bigint(20) NOT NULL ,
  `terminusName` varchar(10) NOT NULL ,
  `firstExpressTime` datetime NOT NULL ,
  `lastExpressTime` datetime NOT NULL ,
  `lineDirection` int(3) DEFAULT '1' ,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `bus_line_to_station` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT ,
  `lineID` bigint(20) NOT NULL ,
  `stationID` bigint(20) NOT NULL ,
  `stationOrder` int(3) NOT NULL ,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `bus_station` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT ,
  `stationName` varchar(20) NOT NULL ,
  `stationLng` double NOT NULL ,
  `stationLat` double NOT NULL ,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

but i worry that if i divide one table into many sub tables,such as

bus_station divided into bus_station1,bus_station2,bus_station3 and so on

bus_line_to_station divided into bus_line_to_station1,bus_line_to_station2,bus_line_to_station3 and so on in the same database.

the hibernate how to deal with the situation?

or i create other two databases,and create table bus_line_to_station1,bus_line_to_station2 ...in database1,and create table bus_station1,bus_station2 ... in database2.

the hibernate how to deal with the situation? thanks for your any help and suggestion in advance.

What you are asking here does not seem to make much sense so probably I do not understand what you want. Please clarify why you want to create additional tables or even db's for what seems to be a straightforward Many2Many relationship (where you would just have 1 additional bus_line_to_station table for the mapping. — Stijn Geukens, Nov 14 '14 at 10:37

score 0 · Accepted Answer · edited May 23 '17 at 11:49

Based on your information you cannot use a ManyToMany since you want to keep additional information on the relation between a bus and a station. In this case you need to create a mapping entity like BusLineToStation with following properties:

Busline (ManyToOne)
Station (ManyToOne)
stationOrder (Integer)
id (optional)

From BusLine and BusStation you can then just have a OneToMany to BustLineToStation.

See also https://stackoverflow.com/a/5127262/190596

hibernate how to deal with divided to many tables

1 Answers1