I. Preface

When we design tables for projects, sometimes we need to use composite primary keys to identify uniqueness. If the project's persistence layer adopts hibernate framework, we can use @ EmbeddedId annotation to achieve this requirement.

2, Table design

CREATE TABLE `mkt_mas_cpcus` (
  `CR_ORG_NBR` decimal(3,0) NOT NULL DEFAULT '0' COMMENT 'Organization number',
  `CR_ACCT_NBR` decimal(16,0) NOT NULL DEFAULT '0' COMMENT 'Cardholder code',
  `CR_STATUS` decimal(1,0) DEFAULT NULL COMMENT 'state',
  `CR_SHORT_NAME` varchar(15) DEFAULT NULL COMMENT 'Full name',
  PRIMARY KEY (`CR_ORG_NBR`,`CR_ACCT_NBR`)
)

In this table, the organization No. CR? Org? NBR and cardholder code CR? Acct? NBR are used as composite primary keys to uniquely identify a piece of data.

3, Create a compound primary key class

@Embeddable
public class MasCpcusPK implements Serializable {
    private static final long serialVersionUID = 1L;

    private BigDecimal crAcctNbr; // Cardholder code
    private BigDecimal crOrgNbr; // Organization number

    public MasCpcusPK() {
    }  
    @Basic
    @Column(name="CR_ACCT_NBR")
    public BigDecimal getCrAcctNbr() {
        return this.crAcctNbr;
    }
    public void setCrAcctNbr(BigDecimal crAcctNbr) {
        this.crAcctNbr = crAcctNbr;
    }
    @Basic
    @Column(name="CR_ORG_NBR")
    public BigDecimal getCrOrgNbr() {
        return this.crOrgNbr;
    }
    public void setCrOrgNbr(BigDecimal crOrgNbr) {
        this.crOrgNbr = crOrgNbr;
    }
}

4, Create po class with hibernate annotation

Replace the two properties with the composite primary key, and add the @ EmbeddedId annotation to the get method.

@Entity
@Table(name = "mkt_mas_cpcus", schema = "market", catalog = "")
public class MktMasCpcus implements Serializable {

    private static final long serialVersionUID = -8509123963537411929L;

    private MasCpcusPK id; // Composite primary key

    private BigDecimal crStatus; // Customer status

    private String crShortName; // Full name

    @EmbeddedId
    public MasCpcusPK getId() {
        return id;
    }

    public void setId(MasCpcusPK id) {
        this.id = id;
    }
    @Basic
    @Column(name = "CR_STATUS")
    public BigDecimal getCrStatus() {
        return crStatus;
    }

    public void setCrStatus(BigDecimal crStatus) {
        this.crStatus = crStatus;
    }

    @Basic
    @Column(name = "CR_SHORT_NAME")
    public String getCrShortName() {
        return crShortName;
    }

    public void setCrShortName(String crShortName) {
        this.crShortName = crShortName;
    }
}

5, Create DAO layer

Since it is a composite primary key, the primary key in the generic must write this composite primary key, MasCpcusPK.

public interface MktMasCpcusDao extends JpaRepository<MktMasCpcus, MasCpcusPK> {

}

If you want to call the interface of Dao layer, when querying according to the id, the id will be passed to MasCpcusPK.