The @NamedQuery and @NamedQueries annotations are used to define one or more JPQL queries. These queries will be associated with that particular entity. @NamedQuery Example: @Entity @NamedQuery(name="Student.selectAllStudents", query="SELECT st FROM Students st") public class Students { … }@Entity @NamedQuery(name="Student.selectAllStudents", query="SELECT st FROM Students st") public class Students { … } @NamedQueries Example: @Entity @NamedQueries({ @NamedQuery(name="Student.selectAllStudents", … Read more

The @ManyToMany annotation is used to implement Many-to-Many relationship. Two entities are said to be in Many-to-Many relationship if many occurrence of entity belongs to many occurrence of other entity and vice versa. Example: // In Customer class: @ManyToMany @JoinTable(name="CUST_PHONES") public Set<PhoneNumber> getPhones() { return phones; }   // In PhoneNumber class: @ManyToMany(mappedBy="phones") public Set<Customer> … Read more

The @ManyToOne annotation is used to implement Many-to-One relationship. Two entities are said to be in Many-to-One relationship if one entity belongs to many occurrence of other entity. Note: One-to-Many and Many-to-One are both same it depends upon the side of entities in the relationship. As one department – many employees refers to the One-to-Many … Read more

The @OneToMany annotation is used to implement One-to-Many relationship. Two entities are said to be in One-to-Many relationship if one entity has many occurrence in other entity. Example: // In Customer class: @OneToMany(targetEntity=com.example.Order.class, cascade=ALL, mappedBy="customer") public Set getOrders() { return orders; }   // In Order class: @ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return … Read more

The @OneToOne annotation is used to implement One-to-One relationship. Two entities are said to be in One-to-One relationship if one entity has only one occurrence in other entity. Example: // On Customer class: @OneToOne(optional=false) @JoinColumn( name="CUSTREC_ID", unique=true, nullable=false, updatable=false) public CustomerRecord getCustomerRecord() { return customerRecord; }   // On CustomerRecord class: @OneToOne(optional=false, mappedBy="customerRecord") public Customer … Read more

The @Temporal annotation is specified for Date and Calendar type persistent. It can have one of following three values DATE, TIME, and TIMESTAMP. Default is TIMESTAMP. Example: @Temporal(TemporalType.TIME) java.util.Date createDtae;@Temporal(TemporalType.TIME) java.util.Date createDtae;

It is used to annotate a property or field of an entity class, mapped superclass, or embeddable class which is not persistent. Example: @Entity public class Employee { @Id int id; @Transient String testField; … }@Entity public class Employee { @Id int id; @Transient String testField; … } In case of above example, testField property … Read more

The Column annotation is used to specify the mapped column for a persistent property or field. If no Column annotation is specified, the default value will be applied. Example: @Column(name="DESC", nullable=false, length=512) public String getDescription() { return description; }@Column(name="DESC", nullable=false, length=512) public String getDescription() { return description; } Attribute: Name: The name of the column. … Read more

The Table annotation is used to specify the primary table for the annotated entity. Additional tables may be specified using SecondaryTable or SecondaryTables annotation. Example: @Entity @Table(name="Student") public class Student {   …   }@Entity @Table(name="Student") public class Student { … } Attribute: Name: The name of the table. It is an optional attribute. Schema: … Read more

The EmbeddableId annotation is used to create a composite primary key. It can also be applied to a persistent field or property of an entity class or mapped superclass to denote a composite primary key that is an embeddable class. Example: @Embeddable public class Zipcode { protected String zip; protected String plusFour; }   @Embeddable … Read more