'SQL JPA - Multiple columns as primary key

If i want severeal Column to make up an ID.

SQL example :

CONSTRAINT [PK_NAME] PRIMARY KEY ([Column1],[Column2],[Column3])

How can i do that with a Jpa Entity class ? through columndefinition ?

just setting the id field as:

value = Column1 + Column2 + Column3 // aint working.
javasqljpaspring-bootentity


Solution 1:[1]

Use @Embeddable and @EmbeddedId.

Example:

@Entity
public class Project implements Serializable {
    @EmbeddedId ProjectId id;
}
 
@Embeddable
class ProjectId implements Serializable {
    int departmentId;
    long projectId;
}

More information here http://www.objectdb.com/java/jpa/entity/id#Embedded_Primary_Key_

Solution 2:[2]

If all fields in the class are part of primary key, then solution would be pretty simple (extending solution provided by @raul-cuth):

@Entity
@IdClass(EntityExample.class)
public class EntityExample implements Serializable {

    @Id
    private int column1;

    @Id
    private int column2;

    @Id
    private int column3;
}

Solution 3:[3]

  1. Using @IdClass annotation on the @Entity class followed by @Id annotation on individual fields that are part of composite primary key.
  2. Alternatively can make use of @Embeddable class which can consist of individual fields of the composite primary key and then a reference of this class can be used as an attribute with @Embedded annotation in @Entity class. Hope this helps.

Solution 4:[4]

Be aware that the hibernate Entity-Class-to-SQL-DDL-Script generator will sort all the fields, and irrespective of the order in which it appears in the definitions, will create the table definition and the index / constraint definitions in this sorted order of the fields.

While the order of appearance of the fields in the table definition may not matter much, the order of fields in a composite index definitely do. So your key-fields must be named so that when sorted by their names they are in the order you desire for the index).

Sources

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Source: Stack Overflow

Solution Source
Solution 1 lorraine
Solution 2 heroin
Solution 3 M. Deinum
Solution 4 Alok P

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