How to Get Multiple Columns from Table Using Jpa

How to select all the data of two columns from a table using JPA query method

Create a result class first:

package com.example;

public class ResultClass{

  private Long id;
  private String name;

  public ResultCalss(Long id, String name){
     // set
  }
}

and then use a custom @Query:

@Query("select new com.example.ResultClass(e.id, e.name) from MyEntity e")
public List<ResultClass> findIdsAndNames();

java- how to return multiple columns in JPA for email?

Try replacing the query call with:

List<Emailqueue> res = em.createQuery("SELECT e from Emailqueue e WHERE e.status='Pending'",
                                          Emailqueue.class).getResultList();

This will return a list of matching instances as Java objects (entities), which you can easily work with by calling getters/setters, for example (using the sendEmail method from your question):

for (Emailqueue eq : res) {
   sendStatus = sendEmail(eq.getRecipient(), eq.getSubject(), eq.getContent(), eq.getId(), eq.getUsername());
}

Or, better yet, change the signature of sendEmail to sendEmail(Emailqueue eq) and call the getters in the method.

use jpa nativequery multiple columns in object list array

I would try to restructure the query as follows:

SELECT * FROM TABLE A
WHERE (A.COL1 = 'val1' and A.COL2 = 'val2')
OR (A.COL1 = 'val3' and A.COL2 = 'val4')

This would allow the query to be constructed as follows:

List<String[]> queryList = new ArrayList<>();
String[] arr = {"val1", "val2"};
String[] arr = {"val3", "val4"};
queryList.add(arr);

String sql = "SELECT * FROM TABLE A "; //dont forget space at end

if (!queryList.isEmpty()){
    sql = sql + "WHERE "; //dont forget space at end


    for (String[] queryParam : queryList ){
        sql = sql + " (A.COL1 = '"+ queryParam[0] + "' and A.COL2 = '" + queryParam[1] + "') OR "; //dont forget space at end and simple colons for param
    }

    //finally remove the last OR.
    Integer indexLastOR = sql.lastIndexOf("OR");
    sql = sql.substring(0, indexLastOR);
}

Query query = entityManager.createNativeQuery(sql);

This will also allow the query to be implemented without being native, which is advisable to maintain the JPA philosophy.

SQL JPA - Multiple columns as primary key

You need to have a class for your composite key:

public class CompositeKey implements Serializable {
    private int column1;
    private int column2;
    private int column3;
}

and then in your entity class use the @IdClass annotation:

@Entity
@IdClass(CompositeKey.class)
public class EntityExample {
    @Id
    private int column1;
    @Id
    private int column2;
    @Id
    private int column3;
    ...
    ...
}

I think this should work. Hope it helps, cheers!

Yea and there is the other solution, the one that @jklee mentioned, both work, it's a matter of preference.

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