We can add table constraint with @Table annotation.
The following table adds unique constraint to Person table on name column.
@Entity @Table(uniqueConstraints=@UniqueConstraint(columnNames="NAME")) public class Person {
The following code is from PersonDaoImpl.java.
package com.java2s.common; import java.util.Calendar; import java.util.List; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import org.springframework.transaction.annotation.Transactional; @Transactional public class PersonDaoImpl { public void test(){ Person p1 = new Person("Tom"); p1.setId(1L); p1.setDob(Calendar.getInstance()); Person p2 = new Person("Jack"); p2.setId(2L); save(p1); save(p2); listAll(); } private void listAll(){ List<Person> persons = getAll(); for (Person person : persons) { System.out.println(person); } } @PersistenceContext private EntityManager em; public Long save(Person person) { em.persist(person); return person.getId(); } public List<Person>getAll() { return em.createQuery("SELECT p FROM Person p", Person.class).getResultList(); } }
The following code is from Person.java.
package com.java2s.common; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.Table; import javax.persistence.Temporal; import javax.persistence.TemporalType; import javax.persistence.UniqueConstraint; @Entity @Table(uniqueConstraints=@UniqueConstraint(columnNames="NAME")) public class Person { @Id private long id; private String name; @Temporal(TemporalType.DATE) private java.util.Calendar dob; public Person() {} public Person(String name) { this.name = name; } public java.util.Calendar getDob() { return dob; } public void setDob(java.util.Calendar dob) { this.dob = dob; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String toString() { return "\n\nID:" + id + "\nName:" + name + "\n\n"+"Dob"+dob; } }
The code above generates the following result.
The following is the database dump.
Table Name: PERSON Row: Column Name: ID, Column Type: BIGINT: Column Value: 1 Column Name: DOB, Column Type: DATE: Column Value: 2014-12-29 Column Name: NAME, Column Type: VARCHAR: Column Value: Tom Row: Column Name: ID, Column Type: BIGINT: Column Value: 2 Column Name: DOB, Column Type: DATE: Column Value: null Column Name: NAME, Column Type: VARCHAR: Column Value: Jack