難點在Hibernate的多對多關係與額外的列使用註釋沒有複合鍵

Question

我已經嘗試了許多與表結構一對多的關係作爲

Programs 
--------- 
Program_cd, 
Program_name 

period_types 
------------- 
period_type_cd, 
Period_type 

Program_period_years 
--------------------- 
Program_cd, 
Period_type_cd, 
year 

按我的表結構關係表中有一個額外的列年。 我定義三個實體程序，preriod_types，program_period_types和船的關係作爲

one to many between program and program_period_types 
one to many between period_types and program_period_types 
many to one between program_period_types and programs 
many to one between program_period_types and period types 

現在的問題是按照代碼中（Program_cd ，Period_type_cd）所做的編碼是充當我不復合鍵希望我希望三列Program_cd，Period_type_cd，year充當主鍵或不充當主鍵。

我可以得到任何建議以及正確的代碼示例。 我已經使用註釋完成了它。

Answer 1

首先，有一些似乎不必要的關係，有些東西可能會簡化您的設計。

首先，你不需要對設計Program和ProgramPeriodType

基地之間的關係，你真正需要的是：

class Program { 
    @Id 
    String code; 

    @OneToMay 
    List<ProgramPeriodYear> years; 
} 

class ProgramPeriodType { 
    @Id 
    String code; 
} 

class ProgramPeriodYear { 
    @ManyToOne 
    Program program; 

    @ManyToOne 
    ProgramPeriodType periodType; 

    String year; 
} 

然後下一個節目是ID的ProgramPeriodYear的選擇，簡而言之，您可以簡單地擁有一個包含program，periodType和year的組合密鑰。其次，如果你的ProgramPeriodType定義是相當靜態的，你可以考慮把它作爲一個枚舉，它省略了ProgramPeriodType實體的需要，並且使periodType成爲一個簡單的列。

Answer 2

the relationships defined are correct 

one to many between program and program_period_types 
one to many between period_types and program_period_types 
many to one between program_period_types and programs 
many to one between program_period_types and period types 

i dont know how to make three column(program_cd,period_type_cd and year) as composite key in the relation table as year is an extra column 
can some one guide me with my code 


------------------------------------------------------------------------------------------- 
Code as follows: 

------------------------------------------------------------------------------------------- 

DROP TABLE IF EXISTS `test`.`programs`; 
CREATE TABLE `test`.`programs` (
    `program_cd` varchar(45) NOT NULL, 
    `program_name` varchar(45) DEFAULT NULL, 
    PRIMARY KEY (`program_cd`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 


DROP TABLE IF EXISTS `test`.`period_types`; 
CREATE TABLE `test`.`period_types` (
    `period_type_cd` varchar(45) NOT NULL, 
    `period_type` varchar(45) NOT NULL, 
    PRIMARY KEY (`period_type_cd`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 


DROP TABLE IF EXISTS `test`.`periods_for_program_and_year`; 
CREATE TABLE `test`.`periods_for_program_and_year` (
    `program_cd` varchar(45) NOT NULL, 
    `year` varchar(45) NOT NULL, 
    `period_type_cd` varchar(45) NOT NULL, 
    PRIMARY KEY (`program_cd`,`year`,`period_type_cd`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 


------------------------------------------------------------------------------------------- 

Entity Clasess: 

------------------------------------------------------------------------------------------- 

Entity class for program table 
-------------------------------------------------------------------------------------- 

package test; 

import java.util.HashSet; 
import java.util.Set; 

import javax.persistence.CascadeType; 
import javax.persistence.Column; 
import javax.persistence.Entity; 
import javax.persistence.FetchType; 
import javax.persistence.GeneratedValue; 
import javax.persistence.GenerationType; 
import javax.persistence.Id; 
import javax.persistence.JoinColumn; 
import javax.persistence.JoinTable; 
import javax.persistence.ManyToMany; 
import javax.persistence.OneToMany; 
import javax.persistence.Table; 
import javax.persistence.UniqueConstraint; 

@Entity 
@Table(name = "programs") 
public class Program_Years implements java.io.Serializable{ 

    private static final long serialVersionUID = 1L; 

    String program_cd; 
    String program_name; 
    private Set<Periods_for_program_and_year> periods_for_program_and_year = new HashSet<Periods_for_program_and_year>(0); 

    public Program_Years() { 
     // TODO Auto-generated constructor stub 
    } 

    public Program_Years(String program_cd, String program_name) { 
     super(); 
     this.program_cd = program_cd; 
     this.program_name = program_name; 
    } 

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.programcd", cascade=CascadeType.ALL) 
    public Set<Periods_for_program_and_year> getPeriods_for_program_and_year() { 
     return periods_for_program_and_year; 
    } 

    public void setPeriods_for_program_and_year(
      Set<Periods_for_program_and_year> periods_for_program_and_year) { 
     this.periods_for_program_and_year = periods_for_program_and_year; 
    } 

    @Id 
    @Column(name = "program_cd" ,unique = true, nullable = false) 
    public String getProgram_cd() { 
     return program_cd; 
    } 
    public void setProgram_cd(String program_cd) { 
     this.program_cd = program_cd; 
    } 

    @Column(name = "program_name", nullable = false, length = 20) 
    public String getProgram_name() { 
     return program_name; 
    } 
    public void setProgram_name(String program_name) { 
     this.program_name = program_name; 
    } 

    @Override 
    public String toString() { 
     return "Program_Years [program_cd=" + program_cd + ", program_name=" 
       + program_name + "]"; 
    } 




} 

----------------------------------------------------- 

Entity class for period types table 
---------------------------------------------------------------------------------------- 

package test; 

import java.util.HashSet; 
import java.util.Set; 

import javax.persistence.Column; 
import javax.persistence.Entity; 
import javax.persistence.FetchType; 
import javax.persistence.Id; 
import javax.persistence.OneToMany; 
import javax.persistence.Table; 

@Entity 
@Table(name = "Period_Types") 
public class Period_Types implements java.io.Serializable{ 

    private static final long serialVersionUID = 1L; 

    String period_type_cd; 

    String period_type; 

    private Set<Periods_for_program_and_year> periods_for_program_and_year = new HashSet<Periods_for_program_and_year>(0); 

public Period_Types() { 
    // TODO Auto-generated constructor stub 
} 

    public Period_Types(String period_type_cd, String period_type) { 
     super(); 
     this.period_type_cd = period_type_cd; 
     this.period_type = period_type; 
    } 

    @Id 
    @Column(name = "period_type_cd",unique = true, nullable = false) 
    public String getPeriod_type_cd() { 
     return period_type_cd; 
    } 

    public void setPeriod_type_cd(String period_type_cd) { 
     this.period_type_cd = period_type_cd; 
    } 

    @Column(name = "period_type", nullable = false, length = 10, unique = true) 
    public String getPeriod_type() { 
     return period_type; 
    } 

    public void setPeriod_type(String period_type) { 
     this.period_type = period_type; 
    } 

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.periodtypecd") 
    public Set<Periods_for_program_and_year> getPeriods_for_program_and_year() { 
     return periods_for_program_and_year; 
    } 

    public void setPeriods_for_program_and_year(
      Set<Periods_for_program_and_year> periods_for_program_and_year) { 
     this.periods_for_program_and_year = periods_for_program_and_year; 
    } 

    @Override 
    public String toString() { 
     return "Period_Types [period_type_cd=" + period_type_cd 
       + ", period_type=" + period_type + "]"; 
    } 




} 
----------------------------------------------------------------------------------- 

Entity class for relational table 
------------------------------------------------------------------------------------ 

package test; 


import javax.persistence.AssociationOverride; 
import javax.persistence.AssociationOverrides; 
import javax.persistence.Column; 
import javax.persistence.EmbeddedId; 
import javax.persistence.Entity; 
import javax.persistence.JoinColumn; 
import javax.persistence.Table; 
import javax.persistence.Temporal; 
import javax.persistence.TemporalType; 
import javax.persistence.Transient; 

@Entity 
@Table(name = "periods_for_program_and_year") 
@AssociationOverrides({ 
     @AssociationOverride(name = "pk.programcd", 
      joinColumns = @JoinColumn(name = "program_cd")), 
     @AssociationOverride(name = "pk.periodtypecd", 
      joinColumns = @JoinColumn(name = "period_type_cd")) }) 
public class Periods_for_program_and_year implements java.io.Serializable{ 

    private static final long serialVersionUID = 4050660680047579957L; 

    private Periods_for_program_and_yearID pk = new Periods_for_program_and_yearID(); 
    private String year; 


    @EmbeddedId 
    public Periods_for_program_and_yearID getPk() { 
     return pk; 
    } 
    public void setPk(Periods_for_program_and_yearID pk) { 
     this.pk = pk; 
    } 

    @Transient 
    public Program_Years getProgramcd() { 
     return getPk().getProgramcd(); 
    } 

    public void setProgramcd(Program_Years c) { 
     getPk().setProgramcd(c); 
    } 


    @Transient 
    public Period_Types getPeriodtypecd() { 
     return getPk().getPeriodtypecd(); 
    } 

    public void setPeriodtypecd(Period_Types c) { 
     getPk().setPeriodtypecd(c); 
    } 


    @Column(name = "year", nullable = false, length = 10) 
    public String getYear() { 
     return year; 
    } 
    public void setYear(String year) { 
     this.year = year; 
    } 


    @Override 
    public int hashCode() { 
     return (getPk() != null ? getPk().hashCode() : 0); 
    } 



    @Override 
    public boolean equals(Object obj) { 
     if (this == obj) 
      return true; 
     if (obj == null) 
      return false; 
     if (!(obj instanceof Periods_for_program_and_year)) 
      return false; 
     Periods_for_program_and_year other = (Periods_for_program_and_year) obj; 
     if (pk == null) { 
      if (other.pk != null) 
       return false; 
     } else if (!pk.equals(other.pk)) 
      return false; 
     if (year == null) { 
      if (other.year != null) 
       return false; 
     } else if (!year.equals(other.year)) 
      return false; 
     return true; 
    } 

    @Override 
    public String toString() { 
     return "Periods_for_program_and_year [pk=" + pk + ", year=" + year 
       + "]"; 
    } 





} 
------------------------------------------------------------------------------------ 
Entity class whhich acts as a composite key 

-------------------------------------------------------------------------------------- 

package test; 

import javax.persistence.Embeddable; 
import javax.persistence.ManyToOne; 

@Embeddable 
public class Periods_for_program_and_yearID implements java.io.Serializable{ 

    private static final long serialVersionUID = -9120607274421816301L; 
    private Program_Years programcd; 
    private Period_Types periodtypecd; 

    @ManyToOne 
    public Program_Years getProgramcd() { 
     return programcd; 
    } 
    public void setProgramcd(Program_Years programcd) { 
     this.programcd = programcd; 
    } 

    @ManyToOne 
    public Period_Types getPeriodtypecd() { 
     return periodtypecd; 
    } 
    public void setPeriodtypecd(Period_Types periodtypecd) { 
     this.periodtypecd = periodtypecd; 
    } 

    @Override 
    public int hashCode() { 
     int result; 
      result = (programcd != null ? programcd.hashCode() : 0); 
      result = 17 * result + (periodtypecd != null ? periodtypecd.hashCode() : 0); 
      return result; 
    } 


    @Override 
    public boolean equals(Object obj) { 
     if (this == obj) 
      return true; 
     if (obj == null) 
      return false; 
     if (!(obj instanceof Periods_for_program_and_yearID)) 
      return false; 
     Periods_for_program_and_yearID other = (Periods_for_program_and_yearID) obj; 
     if (periodtypecd == null) { 
      if (other.periodtypecd != null) 
       return false; 
     } else if (!periodtypecd.equals(other.periodtypecd)) 
      return false; 
     if (programcd == null) { 
      if (other.programcd != null) 
       return false; 
     } else if (!programcd.equals(other.programcd)) 
      return false; 
     return true; 
    } 
    @Override 
    public String toString() { 
     return "Periods_for_program_and_yearID [programcd=" + programcd 
       + ", periodtypecd=" + periodtypecd + "]"; 
    } 




} 

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