Many-to-one | one-to-many

Question

Hi, I am pretty new to berkeley db je. I am trying to devise a good strategy for the following....note these are obviously generic examples. We read the data out of oracle into objects, and wish to use je as a front end cache.
class foo {
long foo_id;
int somedata;
class bar {
long bar_id;
int somedata;
class foobar {
long foo_id;
long bar_id;
int somedata;
foobar is an association between foo and bar. a single foo can be related to many foobars. a single bar can be related to many foobars.
I create a primary database in berkeley for foo and a primary database in berkeley for bar, both using the id as the key.
I create a primary database in berkeley for foobar using foo id as the key. I want to create a secondary database in berkeley for foobar using bar id as the key, but I cannot, b/c the primary database must not support duplicates -- but this breaks the one (foo) to many (foobar) relationship.
What is the best db strategy using je to accomplish what i'm trying to do?
Thanks in advance,
Davis

Answer 1

Hello.
as I still did not solve my problem, I will try to reformulate my question I want to make request EJB3 QL with joint.
here my tables:
    CREATE TABLE `umlssnmi` (
  `AUIS` varchar(20) NOT NULL default '',
  `CUI` varchar(20) NOT NULL default '',
  `CODE` varchar(20) NOT NULL default '',
  `TTY` varchar(5) NOT NULL default '',
  `STR` varchar(255) NOT NULL default '',
  `HIER` varchar(255) NOT NULL default '',
  `PROF` tinyint(2) NOT NULL default '0',
  `AXE` char(1) NOT NULL default 'D',
  PRIMARY KEY  (`AUIS`),
  KEY `CODE` (`CODE`),
  KEY `TTY` (`TTY`),
  KEY `CUI` (`CUI`),
  KEY `AXE` (`AXE`)
) TYPE=MyISAM;
CREATE TABLE `whoart` (
  `AUIW` varchar(10) NOT NULL default '',
  `CODE` varchar(10) NOT NULL default '',
  `STR` varchar(255) NOT NULL default '',
  `FSTR` varchar(255) NOT NULL default '',
  `SOC` varchar(5) NOT NULL default '',
  `SEMTYPE` varchar(5) NOT NULL default '',
  `SRC` enum('WA','CIM') NOT NULL default 'WA',
  PRIMARY KEY  (`AUIW`),
  KEY `SOC` (`SOC`),
  KEY `CODE` (`CODE`)
) TYPE=MyISAM;Knowing that I have the following table which has like clès primary both clès primary of the tables the preceding one.
    CREATE TABLE `wasnmi` (
  `AUIW` varchar(20) NOT NULL default '',
  `AUIS` varchar(20) NOT NULL default '',
  `MODIF` varchar(10) default NULL,
  `SRC` enum('S','MW','MS','MA') NOT NULL default 'S',
  PRIMARY KEY  (`AUIW`,`AUIS`),
  KEY `MOD` (`SRC`),
  KEY `MODIF` (`MODIF`)
) TYPE=MyISAM;
knowing that cardinality between these tables and ManyToMany, my question and to know if so that I can make a join
between my tables I must create tables intermédiates which contain that the primary keys like umlssnmi_wasnmi kind
and whoart_wasnmi for example, and to make @JoinTable; or the table "wasnmi" will join the tables.
I tried to implement :
For table WHOART:
    public class TermSource implements Serializable {
@OneToMany (mappedBy="auiw")
    private Collection<TermProjPK> termProjPks;
    public Collection<TermProjPK> getTermProjPks() {
        return termProjPks;
    public void setTermProjPks(Collection<TermProjPK> termProjPks) {
        this.termProjPks = termProjPks;
}For UMLSSNMI table:
public class SnomedInter implements Serializable {
@OneToMany (mappedBy="auis")
    private Collection<TermProjPK> termProjPks;
    public Collection<TermProjPK> getTermProjPks() {
        return termProjPks;
    public void setTermProjPks(Collection<TermProjPK> termProjPks) {
        this.termProjPks = termProjPks;
}The TermProjPK class which contains the primary keys of table WASNMI:
    @Embeddable
public class TermProjPK implements Serializable {
@ManyToOne
    @JoinColumn(name = "AUIW", nullable = false)
    private String auiw;
    private Collection<TermSource> termSources;
    public Collection<TermSource> getTermSources() {
        return termSources;
    public void setTermSources(Collection<TermSource> termSources) {
        this.termSources = termSources;
@ManyToOne
    @JoinColumn(name = "AUIS", nullable = false)
    private String auis;
    private Collection<SnomedInter> snomedInters;
    public Collection<SnomedInter> getSnomedInters() {
        return snomedInters;
    public void setSnomedInters(Collection<SnomedInter> snomedInters) {
        this.snomedInters = snomedInters;
}For WASNMI table:
    public class TermProj implements Serializable {   
    @EmbeddedId
    protected TermProjPK termProjPK;
    @Column(name = "MODIF")
    private String modif;
    @Column(name = "SRC", nullable = false)
    private String src;
}That does not function, because I do not know how I can reach the fields ` MODIF' and ` SRC' of the table ` WASNMI' starting from TermSource object.
Somebody already made there?. :banghead: I thank you in advance