Errors while executing Select Statement using JPA

Question

I am trying to use Select Query with JPA but i am getting some error:

This is my CountryDto.java file

@Entity    
@Table(name = "COUNTRY")
public class CountryDto {

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)  
   @Column(name="COUNTRY_ID")
   private int Country_Id;
   @Column(name="COUNTRY")
   private String Country;  

   // Getters & Setters go here

   public CountryDto() {
    // TODO Auto-generated constructor stub
   }
   public CountryDto(int country_Id, String country) {
   //   super();
       Country_Id = country_Id;
       Country = country;
   }
}

My Persistence.xml file is as follows:

<persistence-unit name="texttiledb" transaction-type="RESOURCE_LOCAL">
    <class>com.textileworld.mill.Dto.CountryDto</class>
    <properties>
        <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
        <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/texttiledb" />
        <property name="javax.persistence.jdbc.user" value="root" />
        <property name="javax.persistence.jdbc.password" value="root" />
        <property name="eclipselink.logging.level" value="FINE" />
        <property name="eclipselink.ddl-generation" value="create-tables" />
    </properties>
</persistence-unit>

And This is the code that i am trying to run

    EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("texttiledb");
    EntityManager entitymanager = emfactory.createEntityManager();
    entitymanager.getTransaction( ).begin( );
    Query query = entitymanager.createQuery("SELECT c FROM COUNTRY c",CountryDto.class);
         List<CountryDto> rol= (List<CountryDto> ) query.getResultList();
         for (CountryDto con : rol){
             System.out.println(con);
         }

    entitymanager.getTransaction( ).commit( );
    entitymanager.close( );
    emfactory.close( );

But i dont know why is it showing error that he abstract schema type 'COUNTRY' is unknown.

Here is the error that i am getting :

Exception Description: Problem compiling [SELECT c FROM COUNTRY c]
[14, 21] The abstract schema type 'COUNTRY' is unknown.
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1605)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1625)
    at com.textileworld.mill.Dao.CountryDao.main(CountryDao.java:24)
Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Problem compiling [SELECT c FROM COUNTRY c]. 
[14, 21] The abstract schema type 'COUNTRY' is unknown.
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildException(HermesParser.java:155)
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.validate(HermesParser.java:347)
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.populateQueryImp(HermesParser.java:278)
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildQuery(HermesParser.java:163)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:142)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:116)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:102)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:86)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1603)

mhasan · Accepted Answer · 2015-12-03 10:10:27Z

try this... first thing you should use NamedQuery for better performance.

    EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("texttiledb");
    EntityManager entitymanager = emfactory.createEntityManager();
    entitymanager.getTransaction( ).begin( );
    Query query = entitymanager.createNamedQuery("selectAllCountry");
         List<CountryDto> rol= (List<CountryDto> ) query.getResultList();
         for (CountryDto con : rol){
             System.out.println(con);
         }

    entitymanager.getTransaction( ).commit( );
      entitymanager.close( );
      emfactory.close( );

define your named query like this in your CountryDto

@Entity
@NamedQueries({
        @NamedQuery(name = "selectAllCountry", query = "SELECT C FROM CountryDto C")
})
@Table(name = "COUNTRY")
public class CountryDto {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)     
@Column(name="COUNTRY_ID")
private int Country_Id;
@Column(name="COUNTRY")
private String Country;

public String getCountry() {
    return Country;
}
public int getCountry_Id() {
    return Country_Id;
}
public void setCountry(String country) {
    Country = country;
}
public void setCountry_Id(int country_Id) {
    Country_Id = country_Id;
}
public CountryDto() {
    // TODO Auto-generated constructor stub
}
public CountryDto(int country_Id, String country) {
//  super();
    Country_Id = country_Id;
    Country = country;
}

Abdelhak · Accepted Answer · 2015-12-03 10:18:37Z

1

Try just to use this query:

"SELECT c FROM CountryDto c"

Instead of this:

"SELECT c FROM COUNTRY c"

The @Table(name = "COUNTRY") annotation is used for DB.

answered Dec 3, 2015 at 10:18

Abdelhak

8,4154 gold badges25 silver badges37 bronze badges

Comments

tharindu_DG · Accepted Answer · 2015-12-03 10:27:15Z

0

Change the query as follows.

Query query = entitymanager.createQuery("SELECT c FROM CountryDao c ",CountryDto.class);

Remember the following.

@Table is optional. @Entity is needed for annotating a POJO class as an entity

If the entity is created as the following,

 @Entity(name="MyEntityName")
 @Table(name="MyEntityTableName")
 class MyEntity {

then a table with name MyEntityTableName is created and the entity name is MyEntityName.

Your JPQL query would be :

select * from MyEntityName

Or, if the entity is created as the following,

@Entity
 class MyEntity {

A table with name MyEntity will be created and the Entity name will be MyEntity.

Your JPQL query would be:

select * from MyEntity

Hope this helps.

edited Dec 3, 2015 at 10:27

answered Dec 3, 2015 at 10:17

tharindu_DG

9,2997 gold badges55 silver badges69 bronze badges

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