In Hibernate 3, is there a way to do the equivalent of the following MySQL limit in HQL?
select * from a_table order by a_table_column desc limit 0, 20;
I don't want to use setMaxResults if possible. This definitely was possible in the older version of Hibernate/HQL, but it seems to have disappeared.
This was posted on the Hibernate forum a few years back when asked about why this worked in Hibernate 2 but not in Hibernate 3:
Limit was never a supported clause
in HQL. You are meant to use
setMaxResults().
So if it worked in Hibernate 2, it seems that was by coincidence, rather than by design. I think this was because the Hibernate 2 HQL parser would replace the bits of the query that it recognised as HQL, and leave the rest as it was, so you could sneak in some native SQL. Hibernate 3, however, has a proper AST HQL Parser, and it's a lot less forgiving.
I think Query.setMaxResults() really is your only option.
// SQL: SELECT * FROM table LIMIT start, maxRows;
Query q = session.createQuery("FROM table");
q.setFirstResult(start);
q.setMaxResults(maxRows);
If you don't want to use setMaxResults() on the Query object then you could always revert back to using normal SQL.
The setFirstResult and setMaxResults Query methods
For a JPA and Hibernate Query, the setFirstResult method is the equivalent of OFFSET, and the setMaxResults method is the equivalent of LIMIT:
List<Post> posts = entityManager.createQuery("""
select p
from Post p
order by p.createdOn
""")
.setFirstResult(10)
.setMaxResults(10)
.getResultList();
The LimitHandler abstraction
The Hibernate LimitHandler defines the database-specific pagination logic, and as illustrated by the following diagram, Hibernate supports many database-specific pagination options:
Now, depending on the underlying relational database system you are using, the above JPQL query will use the proper pagination syntax.
MySQL
SELECT p.id AS id1_0_,
p.created_on AS created_2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
LIMIT ?, ?
PostgreSQL
SELECT p.id AS id1_0_,
p.created_on AS created_2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
LIMIT ?
OFFSET ?
SQL Server
SELECT p.id AS id1_0_,
p.created_on AS created_on2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
OFFSET ? ROWS
FETCH NEXT ? ROWS ONLY
Oracle
SELECT *
FROM (
SELECT
row_.*, rownum rownum_
FROM (
SELECT
p.id AS id1_0_,
p.created_on AS created_on2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
) row_
WHERE rownum <= ?
)
WHERE rownum_ > ?
The advantage of using setFirstResult and setMaxResults is that Hibernate can generate the database-specific pagination syntax for any supported relational databases.
And, you are not limited to JPQL queries only. You can use the setFirstResult and setMaxResults method seven for native SQL queries.
Native SQL queries
You don't have to hardcode the database-specific pagination when using native SQL queries. Hibernate can add that to your queries.
So, if you're executing this SQL query on PostgreSQL:
List<Tuple> posts = entityManager.createNativeQuery(
SELECT
p.id AS id,
p.title AS title
from post p
ORDER BY p.created_on
""", Tuple.class)
.setFirstResult(10)
.setMaxResults(10)
.getResultList();
Hibernate will transform it as follows:
SELECT p.id AS id,
p.title AS title
FROM post p
ORDER BY p.created_on
LIMIT ?
OFFSET ?
Cool, right?
Beyond SQL-based pagination
Pagination is good when you can index the filtering and sorting criteria. If your pagination requirements imply dynamic filtering, it's a much better approach to use an inverted-index solution, like ElasticSearch.
If you don't want to use setMaxResults, you can also use Query.scroll instead of list, and fetch the rows you desire. Useful for paging for instance.
You can easily use pagination for this.
#QueryHints({ #QueryHint(name = "org.hibernate.cacheable", value = "true") })
#Query("select * from a_table order by a_table_column desc")
List<String> getStringValue(Pageable pageable);
you have to pass new PageRequest(0, 1)to fetch records and from the list fetch the first record.
You need to write a native query, refer this.
#Query(value =
"SELECT * FROM user_metric UM WHERE UM.user_id = :userId AND UM.metric_id = :metricId LIMIT :limit", nativeQuery = true)
List<UserMetricValue> findTopNByUserIdAndMetricId(
#Param("userId") String userId, #Param("metricId") Long metricId,
#Param("limit") int limit);
String hql = "select userName from AccountInfo order by points desc 5";
This worked for me without using setmaxResults();
Just provide the max value in the last (in this case 5) without using the keyword limit.
:P
My observation is that even you have limit in the HQL (hibernate 3.x), it will be either causing parsing error or just ignored. (if you have order by + desc/asc before limit, it will be ignored, if you don't have desc/asc before limit, it will cause parsing error)
If can manage a limit in this mode
public List<ExampleModel> listExampleModel() {
return listExampleModel(null, null);
}
public List<ExampleModel> listExampleModel(Integer first, Integer count) {
Query tmp = getSession().createQuery("from ExampleModel");
if (first != null)
tmp.setFirstResult(first);
if (count != null)
tmp.setMaxResults(count);
return (List<ExampleModel>)tmp.list();
}
This is a really simple code to handle a limit or a list.
Criteria criteria=curdSession.createCriteria(DTOCLASS.class).addOrder(Order.desc("feild_name"));
criteria.setMaxResults(3);
List<DTOCLASS> users = (List<DTOCLASS>) criteria.list();
for (DTOCLASS user : users) {
System.out.println(user.getStart());
}
Below snippet is used to perform limit query using HQL.
Query query = session.createQuery("....");
query.setFirstResult(startPosition);
query.setMaxResults(maxRows);
You can get demo application at this link.
You can use below query
NativeQuery<Object[]> query = session.createNativeQuery("select * from employee limit ?");
query.setparameter(1,1);
#Query(nativeQuery = true,
value = "select from otp u where u.email =:email order by u.dateTime desc limit 1")
public List<otp> findOtp(#Param("email") String email);
I have a query that uses projections, it works well as long as the return type is List, but it stops working after adding pagination.
Here is the the working code:
#Query("SELECT DISTINCT \n" +
" new com.mycompany.dto.MyDto(me.property1, me.property2, ...) \n" +
"FROM MyEntiry me...")
List<MyDto> findEntities();
I need to extend it adding pagination, so I change it to:
#Query("SELECT DISTINCT \n" +
" new com.mycompany.dto.MyDto(me.property1, me.property2, ...) \n" +
"FROM MyEntiry me...")
Page<MyDto> findEntities(Pageable pageable);
Once I do that the context starts failing because while parsing it inserts select count(me) between SELECT and FROM statements so that the query become invalid:
SELECT DISTINCT
new com.mycompany.dto.MyDto(me.property1, me.property2, ...)
select count(me) FROM com.mycompany.MyEntiry me ...
The context fails with the following exception:
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException:
unexpected token: select near line 3, column 1 [SELECT DISTINCT new
com.mycompany.dto.MyDto(me.property1, me.property2, ...) select
count(me) FROM com.mycompany.MyEntiry me ...]
at org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:74)
at org.hibernate.hql.internal.ast.ErrorCounter.throwQueryException(ErrorCounter.java:91)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:291)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:186)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:141)
at org.hibernate.engine.query.spi.HQLQueryPlan.(HQLQueryPlan.java:115)
at org.hibernate.engine.query.spi.HQLQueryPlan.(HQLQueryPlan.java:77)
at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153)
at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:553)
at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:662)
... 88 more
Question: How to make it work? Is it Spring Data bug?
Note:
The query I added is oversimplified, my real query in fact gathers different values from different tables and I can't implement it without projections
I'm using Spring Boot 1.5.8.RELEASE
Try to use 'native' Spring Data JPA projections.
This should work well:
public interface MyProjection {
String getProperty1();
//...
}
Page<MyProjection> getDistinctAllBy(Pageable pageable);
But, if your query joins many tables you cannot use the pagination without some pain (for example: 1, 2)
UPDATED
Try to add parameter countQuery to #Query annotation:
#Query(value = "select ...", countQuery = "select count(me) from MyEntiry me")
Page<MyDto> findEntities(Pageable pageable);
I want to get the latest record from a table. My sql is as follow.
Select * from (select * from TABLE_1 WHERE paid=1 order by PAYMENTDATE
DESC) WHERE ROWNUM = 1
I tried to do it with HQL with the mapping pojo classes. It gave errors. My HQL is as follow.
SELECT pay FROM (SELECT payment FROM com.Table1 as payment WHERE
payment.paid=1 ORDER BY payment.paymentDate DESC) as pay where
pay.ROWNUM = 1
The error is,
net.sf.hibernate.QueryException: in expected: SELECT [SELECT pay FROM
(SELECT payment FROM com.TABLE1 as payment WHERE payment.paid=1 ORDER
BY payment.paymentDate DESC) as pay.ROWNUM = 1 ]
Normal queries without subqueries are working.
Eg:
SELECT payment FROM com.Table1 as payment WHERE payment.paid=1
Please help to solve this.
I've successfully created some JPA 2 criteria queries, but im now converting a query that is too complex for me to be able to convert it. Anyone up for a challenge? I will be eternally thankful for any response! :)
This is the query in plain SQL (mysql):
SELECT o.orderId, oi.insertDate
FROM AIDA_ORDER o
LEFT OUTER JOIN
(SELECT orderId, MIN(insertDate) AS insertDate FROM AIDA_ORDER_INSERT
WHERE insertDate > CURDATE() GROUP BY orderId) AS oi
ON oi.orderId = o.orderId
ORDER BY oi.insertDate, o.orderId;
The AIDA_ORDER table corresponds to a OrderBean, and AIDA_ORDER_INSERT to a OrderInsertBean.
A AIDA_ORDER can have multiple AIDA_ORDER_INSERTS.
Excuse me for anking again about this issue but I need to have a JPA query for this:
select username, count(*)
from Records
group by username
order by count(*) desc
limit 1
I thought about smth like:
select r.username,count(*) from Records r order by r.username desc
and then to call
getResultList().get(0)
but I am allowed to write only:
select r from Records r order by r.username desc
and in this case I do not know how to get what I need.
Does anyone have any idea?
The SQL query has a group by, and orders by count. The JPA query doesn't have any group by and orders by user name. So I don't see how they could return the same thing.
The equivalent JPQL query is
select r.username, count(r.id)
from Record r
group by r.username
order by count(r.id) desc
If you call setMaxResults(1) on the Query object, the limit clause will be added to the generated SQL query, making it completely equivalent.