I am a newbie in Query DSL. Now i need to write this simple query in Query DSL:
select * from parent_msq pm left join child_msg cm on (cm.id = pm.id)
I try do like this:
QParentMsg qParentMsg = QParentMsg.parentMsg;
QChildMsg qChildMsg = QChildMsg.childMsg;
JPAQuery q = new JPAQuery(em);
q.from(qParentMsg).leftJoin(qParentMsg.id, qChildMsg).on(qParentMsg.id.eq(qChildMsg.id));
What am I doing wrong?
If the relationship between ParentMsg and ChildMsg entities isn't defined, Hibernate Version Prior to Hibernate 5.1 will not allow the join.
if you are using hibernate 5.1 or later, the following will work.
q.from(qParentMsg).leftJoin(qChildMsg).on(qParentMsg.id.eq(qChildMsg.id));
Related
So I have a SQL query like this,
SELECT *
FROM USERS.NAMES UN
JOIN USERS.ADDRESS UA
ON ADDRESS_TYPE IN ('{user_supplied_value_1}', '{user_supplied_value_2}')
AND UN.USERS_ID = UA.USERS_ID
WHERE UN.NAMES_ID = '{user_supplied_value}'
How can I write a derived JPA query for this without having to use a native query?
I was thinking of something along the lines of this,
List<Names> findAllByNamesIdAndAddressTypeIn
This is the native query -
#Query(nativeQuery = true, value = "SELECT CA FROM CLASS_ATTRIBUTE,WORD_PROCESSING WHERE ( word_processing.uoid = class_attribute.c_user_explanation(+)) ORDER BY CLASS_ATTRIBUTE.DESCRIPTION ASC
I tried the following JPQL query, but it didn't work -
#Query(value = "SELECT CA FROM ClassAttribute CA LEFT JOIN CA.WordProcessing AS WP ON ( WP.id = CA.userExplanationUoid) ORDER BY CA.description ASC")
Also tried the following JPQL -
#Query(value = "SELECT CA FROM ClassAttribute CA LEFT OUTER JOIN CA.WordProcessing AS WP WHERE ( WP.id = CA.userExplanationUoid) ORDER BY CA.description ASC")
The compilation goes into an infinite loop if I try these. Something from the Spring framework is causing it to refresh again and again. There seems to be some issue with the syntax of the converted JPQL query.
It appears that here the issue was with the pom.xml where hibernate.entitymanager.version was 5.0.12.Final. Changing it to 5.1.10.Final did the trick for me.
Since hibernate.entitymanager is now deprecated by Maven (https://mvnrepository.com/artifact/org.hibernate/hibernate-entitymanager), it actually downloaded the jar hibernate-core:5.1.10.Final because of which JOIN related queries are working fine now.
I'm using PostgreSQL in my java application without ORM. I want to go further and add Hibernate to my project. I have this sql query which I add to PreparedStatement() and it returns a number.
SELECT COUNT(pr.id) FROM prisoner pr
JOIN cell c ON c.id = pr.cell_id
JOIN prison p ON p.id = c.prison_id
WHERE p.id = ?
I'm new to Hibernate. How would you suggest me to rewrite this statement to work with Hibernate? Should I use HSQL, or criteria or query or something different ?
You can do it Either of following way.
1) Keep you query as it and use nativeSQL for hibernate.
hibernate native query, count
2) make model of all your join table and put hibernate query.
I am facing problem of executing the following query in java using hibernate for postgres tables.
The query is made up to retrive the data from 3 tables using Inner Joins.
Query :
QryJourney = "SELECT journey.id , journey.operatingday, journey.linename, journey.scheduledeparture, journey.scheduledeparturestopname, journeydetail.stopname , journeydetail.latitude, journeydetail.longitude FROM journey left join journey_journeydetail ON journey.id = journey_journeydetail.journey_id left JOIN journeydetail ON journey_journeydetail.journeydetails_id = journeydetail.id WHERE journey.id = '155815228' ORDER BY journeydetail.schedulearrival";
as soon as it executes, following exception occured.
Exception :
Exception in thread "main" org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: ON near line 1, column 268 [SELECT journey.id , journey.operatingday, journey.linename, journey.scheduledeparture, journey.scheduledeparturestopname, journeydetail.stopname , journeydetail.latitude, journeydetail.longitude FROM de.db.journeyTracker.model.journey left join journey_journeydetail ON journey.id = journey_journeydetail.journey_id left JOIN journeydetail ON journey_journeydetail.journeydetails_id = journeydetail.id WHERE journey.id = '155815228' ORDER BY journeydetail.schedulearrival]
Tis query works 100% fine at postgres while executing on its SQL Pane.
Anybody having any idea?
Regards
Usman
Hibernate queries are written in Hibernate Query Language (HQL) not in native SQL. Rephrase your query in HQL or use a native query to use SQL with Hibernate.
Hibernate is an object-relational mapper. It won't just give you a result set. If you want that, use JDBC directly, using PgJDBC.
If you want native domain objects as query results, use Hibernate with HQL or via a native query mapping. Native queries are fiddlier becuse you have to explicitly tell Hibernate how all the result columns map to your result objects.
Is there a tool able to generate java hibernate code starting from the sql query?
(like reverse of what hibernate does, generating selects from java code) It will help me move all my queries to hibernate!
I mean if i have a select with parameters like this:
select ta.id label, ta.nume value
from ar
left outer join ta ta on idp = ta.ID
where ta.status = 1
and (dp = 0 OR ps = idps_)
and status = 1
order by ta.nume;
to obtain in the end something like this:
DetachedCriteria criteria = DetachedCriteria.forEntityName("ar");
criteria.createAlias("ta", "ta", Criteria.LEFT_JOIN);
criteria.add(Restrictions.eq("ta.status", 1));
Criterion eq = Restrictions.eq("ps.id", idps_);
Criterion isZero = Restrictions.eq("dp.id", 0);
Criterion or = Restrictions.or(eq, isZero);
criteria.add(or);
criteria.add(Restrictions.eq("status", 1));
ProjectionList projectionList = Projections.projectionList();
projectionList.add(Projections.property("ta.id"), "value");
projectionList.add(Projections.property("ta.nume"), "label");
criteria.setProjection(Projections.distinct(projectionList));
criteria.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
criteria.addOrder(Order.asc("ta.nume"));
OR something similar using maps as output...
providing to the tool the path where i store the mappings of the entities/beans with the tables (or the path to the beans, if the beans are annotated)
You have the HQL that is an SQL-like dialect to work with Hibernate. You use field names from entities instead of those from tables. It supports joins etc.
In fact, Criteria API has very limited support of joins (at least it was so last time I've tried to used) and I've a few times finished rewriting everything from Criteria API to HQL, so I now simply tread Criteria API as no option.
In HQL you can also use SQL functions, both in SELECT and in WHERE part, those embedded and those you've written yourself.