为什么我无法从表中获取数据？

Question

There is table named leagues , created as :

CREATE TABLE leagues(id INT NOT NULL AUTO_INCREMENT,lname VARCHAR(255),
                       season VARCHAR(255),PRIMARY KEY (lname),KEY id(id));

For which a mapping hibernate xml is :

<hibernate-mapping>
<class name="pojo.Leagues" table="leagues">
  <id column='lname' name='leaguename' type="string">  </id>
  <property column="id" name="id" type="integer" />
  <property column="season" name="season" type="string" />
</class>
</hibernate-mapping>

I am trying to get data from the leagues table, but I am unable to. Here is the method that is meant to do it:

Query returns nothing and code never enters the loop.

public LinkedList<String> getLeagues() {
    String hql = "select leaguename from pojo.Leagues";
    lnames = new LinkedList<String>();
    Configuration configuration = new Configuration().configure();
    SessionFactory sessFact = configuration.buildSessionFactory();
    Session sess = sessFact.openSession();

    Query query = sess.createQuery(hql);
    List list = query.list();
    System.out.println("Heyyyyyyy:ll");
    Iterator i = list.iterator();
    while(i.hasNext()) {
        System.out.println("Inside while block");
        Leagues lname = (Leagues)i.next();
        lnames.add(lname.getLeaguename());
    }
    return lnames;
}

Where am I making a mistake? Why I am unable to fetch data?

Answer 1

The reason why you didn't get any data from the DB is you are using pure SQL query & calling

Query query = sess.createQuery(hql);

which works on HQL as per createQuery() - Hibernate Doc .

If you want to use pure SQL query then you must use createSQLQuery() - Hibernate Doc

String sqlQuery = "select leaguename from pojo.Leagues";
SQLQuery query = sess.createSQLQuery(sqlQuery);

or change your query in HQL format just like below

String hqlQuery = "from pojo.Leagues";