I use this code to query a table:

Session session;
Transaction tx;
Query query;
List list = null;
try {
SessionFactory sf = new Configuration().configure().buildSessionFactory();
session = sf.openSession();
tx = session.beginTransaction();

String hql="from Patient";
query=session.createQuery(hql);

list=query.list();
session.close();
sf.close();
} catch (Exception e) {
e.printStackTrace();
}
But got this error:

Caused by: java.sql.SQLSyntaxErrorException: Syntax error: Encountered "from" at line 1, column 9.

on your entities what is the name of your table ?
Is it extremely as you type it ? capital P or lower p ?

EDIT : extremely ? Exactly i mean ...
if you have Patient.java then that is not it, if you have patient.java try it with lower letter

The table is "Patient". The error is not related the table name. Nometter what table name I input, it always produce the same error:
net.sf.hibernate.exception.SQLGrammarException: Could not execute query
at net.sf.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:58)
at net.sf.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
at net.sf.hibernate.impl.SessionImpl.convert(SessionImpl.java:4131)
at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1557)
at net.sf.hibernate.impl.QueryImpl.list(QueryImpl.java:49)
at db.SearchDatabase.main(SearchDatabase.java:47)
Caused by: java.sql.SQLSyntaxErrorException: Syntax error: Encountered "from" at line 1, column 9.
at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedPreparedStatement.<init>(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedPreparedStatement20.<init>(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedPreparedStatement30.<init>(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedPreparedStatement40.<init>(Unknown Source)
at org.apache.derby.jdbc.Driver40.newEmbedPreparedStatement(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
at net.sf.hibernate.impl.BatcherImpl.getPreparedStatement(BatcherImpl.java:263)
at net.sf.hibernate.impl.BatcherImpl.getPreparedStatement(BatcherImpl.java:236)
at net.sf.hibernate.impl.BatcherImpl.prepareQueryStatement(BatcherImpl.java:67)
at net.sf.hibernate.loader.Loader.prepareQueryStatement(Loader.java:784)
at net.sf.hibernate.loader.Loader.doQuery(Loader.java:269)
at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:138)
at net.sf.hibernate.loader.Loader.doList(Loader.java:1063)
at net.sf.hibernate.loader.Loader.list(Loader.java:1054)
at net.sf.hibernate.hql.QueryTranslator.list(QueryTranslator.java:854)
at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1554)
... 2 more
Caused by: java.sql.SQLException: Syntax error: Encountered "from" at line 1, column 9.
at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
... 25 more
Caused by: ERROR 42X01: Syntax error: Encountered "from" at line 1, column 9.
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
at org.apache.derby.impl.sql.compile.ParserImpl.parseStatement(Unknown Source)
at org.apache.derby.impl.sql.GenericStatement.prepMinion(Unknown Source)
at org.apache.derby.impl.sql.GenericStatement.prepare(Unknown Source)
at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(Unknown Source)
... 19 more

It seems that the HQL search sentence is wrong.

String hql="from ";

Patient should be class name if yes and you are still getting error then try
from Patient patient. That would resolved your problem.But still i would say that there is problem to register Patient class with Hibernate.Please post your hibernate log to us

Hi,

The class is PatientList and the table is Patient. They are defined in a configuration file Patient.hbm.xml:

<class
name="db.PatientList"
table="Patient"
dynamic-update="false"
dynamic-insert="false"
select-before-update="false"
optimistic-lock="version"
>

I can insert a PatientList instance into Patient table. the problem will happen when query the table.
Where can I find the hibernate log file? I found that there are some log files in the database/log directory. But I can't read it.

I think you actually want to execute "from PatientList"

yes i think so too.
either PatientList
or db.PatientList

Logs should be in your servers ( JBoss, Tomcat ) folder, somewhere in there !