CODEWITHSUNDEEP
javahibernatehql
saplingPro
saplingPro

Reputation: 21329

Getting an exception as I try to run a query. Why is that?

The following snippet throws an exception :

String hqlSelectDB = "use librarian";
sess.createQuery(hqlSelectDB).list();

Exception

java.lang.IllegalArgumentException: node to traverse cannot be null!
org.hibernate.hql.ast.util.NodeTraverser.traverseDepthFirst(NodeTraverser.java:31)
org.hibernate.hql.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:254)
org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:157)
org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)
org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)
org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:56)
org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:72)
org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:133)
org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:112)
org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1623)
servlets.InsertPerson.doPost(InsertPerson.java:41)
javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

Why am I getting this exception ?

Upvotes: 0

Views: 105

Answers (3)

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35597

Query you are going to use is not a HQL query

From librarian

will work

Upvotes: 0

sanbhat
sanbhat

Reputation: 17622

use librarian is not a valid query and its not returning any result.

Try some valid query as from librarian.SomeTable t

If you have a look at Hibernate Configuration, you need to specify which DB you want to use, during configuration phase itself.

This is the example of hibernate configuration property file, which will be used by hibernate to make a SessionFactory (A kind of Connection pool), which will give the DB Connection.

hibernate.connection.driver_class = org.postgresql.Driver
hibernate.connection.url = jdbc:postgresql://localhost/mydatabase --> This is where you specify your DB name
hibernate.connection.username = myuser
hibernate.connection.password = secret
hibernate.c3p0.min_size=5
hibernate.c3p0.max_size=20
hibernate.c3p0.timeout=1800
hibernate.c3p0.max_statements=50
hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect

Upvotes: 1

M Sach
M Sach

Reputation: 34424

It should be

String hqlSelectDB = "from librarian";// where librarian is data object mapped with DB table
sess.createQuery(hqlSelectDB).list();

Upvotes: 0

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