Basic Hibernate Select all Syntax

Question

I am trying to retrieve data from my database with hibernate but it keeps throwing an exception

2012-11-11 11:35:45,943 [main] ERROR com.storage.hibernate.DatabaseAccessRequestsImpl - there was an error javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute query

@Override
public List<Trade> requestPeriod() {
    List<Trade> trades = null;
    EntityManager manager = emf.createEntityManager();
    Query query = manager.createQuery("from trade"); 
    try{
        trades = query.getResultList();
    }
    catch(PersistenceException e){
        logger.error("there was an error " + e);
    }
    catch(SQLGrammarException e){
        logger.error("there was an error " + e);
    }
    return trades;
}

I am guessing the syntax I am using for select all is incorrect but after looking around I can not see an alternative?

Thanks

it should be _"from Trade"_ (uppercase T) if Trade is the name of the mapped class — guido, Nov 11 '12 at 11:44
@guido this indeed was the correct answer - thank you so much — Biscuit128, Nov 11 '12 at 11:49
@guido: please turn your comment into an answer. I added a bit of more details, but the credit should go to you. *SkyR*, please do not accept my answer, I wasn't first :-). — Tomasz Nurkiewicz, Nov 11 '12 at 11:54
@TomaszNurkiewicz thanks, I just added a comment because it could have been just a typo — guido, Nov 11 '12 at 12:02
Actually, @guido didn't mention the need for " t" on the end, which is what was the problem causing a grammar exception (having a bad entity name would get a `QuerySyntaxException: trade is not mapped`). — Tom Anderson, Nov 11 '12 at 12:04
Hmm. Except for me, with Hibernate 4.1.4, "from Trade" works fine, even without the " t". A mystery remains here ... — Tom Anderson, Nov 11 '12 at 12:08
@TomAnderson that's actually something that only happens using JPA over hibernate I think. Minimal JPQL query would also include SELECT (_SELECT e FROM Entity [AS] e_); but something just like "from Class" is valid in HQL and (mistakenly? I think so) works in hibernate's JQPL. — guido, Nov 11 '12 at 12:10
@guido: Ah yes, that's possible. In any case, you're right, it's not standard JPQL, so we shouldn't worry too much about it! — Tom Anderson, Nov 11 '12 at 12:18

score 10 · Accepted Answer · answered Nov 11 '12 at 12:01

10

It should be "from Trade" (uppercase T) as Trade is the name of the mapped class.

answered Nov 11 '12 at 12:01

guido

18,864
6
70
95

score 6 · Answer 2 · edited Jun 20 '20 at 09:12

Note that in JPA QL SELECT clause is mandatory, as per: 10.2.1.1. JPQL Select Statement:

A select statement is a string which consists of the following clauses:

a SELECT clause, which determines the type of the objects or values to be selected;

a FROM clause, which provides declarations that designate the domain to which the expressions specified in the other clauses of the query apply;

[...]

In BNF syntax, a select statement is defined as:
select_statement ::= select_clause from_clause [where_clause] [groupby_clause] [having_clause] [orderby_clause]

The bare from Trade syntax is Hibernate-specific, to be specification compliant you should always use:

select t from Trade t

This helped me in selecting all values from one table and none from another. Big Thank You! — Varun Garg, Jul 08 '15 at 10:09

Basic Hibernate Select all Syntax

2 Answers2

Linked