I'm building a select that has to get me all distinct values from a table.
The sql I would normally write would look like this: "SELECT DISTINCT ARTIST FROM MUSICLIB"
However, ebean is generating the following: "SELECT DISTINCT ID, ARTIST FROM MUSICLIB"
The finder is as such:
find.select("artist").setDistinct(true).findList();
I've found that ebean is generating this ID on every single query, no matter what options I set.
How do I accomplish what I'm looking for?
You can't do that, Ebean for objects mapping requires ID field, and if you won't include it you'll get some mysterious exceptions.
Instead you can query DB without mapping and then write your SQL statement yourself:
SqlQuery sqlQuery = Ebean.createSqlQuery("SELECT DISTINCT artist FROM musiclib");
List<SqlRow> rows = sqlQuery.findList();
for (SqlRow row : rows) {
debug("I got one: " + row.getString("artist"));
}
Of course if artist is a relation, you need to perform additional query using list of found IDs with in(...) expression.
Related
I have a requirement for a Input record with id1 from source, in target table I need to update value v1 in column c1 and in target for id1 there are multiple records. Using JPA I need to update all those records with value v1. Using JPA what is the best way to do this?
I used below
findallbyid() then saveall() - it failed saying there are mutliple records in target but expected was one.
Based on the details provided findallbyid() then saveall()
here the method findallbyid() is actually expecting to find only one record in the table, where as there are multiple rows.
changing the to signature of the method should work as expected without expection. As it expect capitalised words in method signature
https://docs.spring.io/spring-data/jpa/docs/current/api/org/springframework/data/jpa/repository/JpaRepository.html
List<T> findAllById(Long id);
but recommend not to read all rows and then save again just to update a column or two, you could use something like below to achieve the same
#Modifying
#Transactional
#Query(value = "UPDATE table t SET t.column = :status WHERE t.id = :id")
int update(#Param("status") String status, #Param("id") Long id);
In our (ancient) project, we use loads of select queries with HQL on Hibernate version 3.5.6-Final. Because Hibernate will do an auto-commit, because it doesn't know they are select queries, I'm in the process of rewriting all HQL select queries to Hibernate Criteria queries so it won't do in-between commits when we don't want it yet. This is pretty straight-forward in most cases, but I'm currently looking at a query like this, and I'm not sure how to transform it:
Query query = session.createQuery("select municapilityStreet"
+ " from MunicapilityStreet munStreet, Street street"
+ " where munStreet.id = street.MunicapilityStreet.id"
+ " and street.id = :streetId");
query.setParameter(":streetId", streetId);
MunicapilityStreet result = (MunicapilityStreet) query.uniqueResult();
return result;
Here what I have thus far in the process of transforming it:
Criteria criteria = session.createCriteria(MunicapilityStreet.class);
// No idea what to set here to only get the "municapilityStreet" as result
criteria.setProjection(??);
// I'm not sure if this is correct. With a criteria on a single table it would have been simply "Id".
// Both tables have the column-name Id, and I'm not sure how to differentiate between them.
criteria.add(Restrictions.eq("Street.Id", streetId));
MunicapilityStreet result = (MunicapilityStreet) criteria.uniqueResult();
return result;
Maybe I should create a different question for each, but converting the above HQL query to a Criteria has three points I'm not sure about how to do:
How to do a select with multiple tables (the from MunicapilityStreet munStreet, Street street part)?
How to have a projection to only return a single table of the two (the select municapilityStreet part)?
How to have an equal-Restriction on a column name of one table, even though both tables have the same column-name (the and street.id = :streetId part)?
I do oppose the rewrite approach, I hope I'm not impolite doing so.
Hibernate allows to control commits (autocommit is by default off), and what you're experiencing are Entitymanager-flushes, they are auto by default and can be disabled too. And, finally, I think, there is no difference if you're running HQL or criteria queries, same machinery underneath.
I am absolutly new in Hibernate and I have the following problem.
I have this standard SQL query:
SELECT count(*)
FROM TID003_ANAGEDIFICIO anagraficaEdificio
INNER JOIN TID002_CANDIDATURA candidatura
ON (candidatura.PRG_PAR = anagraficaEdificio.PRG_PAR AND candidatura.PRG_CAN = anagraficaEdificio.PRG_CAN)
INNER JOIN TID001_ANAGPARTECIPA anagPartecipa ON(anagPartecipa.PRG_PAR = candidatura.PRG_PAR)
INNER JOIN anagrafiche.TPG1029_PROVNUOIST provNuovIst ON (provNuovIst.COD_PRV_NIS = anagPartecipa.COD_PRV_NIS)
WHERE anagraficaEdificio.FLG_GRA = 1 AND provNuovIst.COD_REG = "SI";
This works fine and return an integer number.
The important thing to know is that in this query the only
parameter that can change (inserted by the user in the frontend of a webappplication) is the last one (this one: provNuovIst.COD_REG = "SI").
So, the application on which I am working use Hibernate and the requirement say that I have to implement this query using Hibernate Native SQL, I have found this tutorial:
http://www.tutorialspoint.com/hibernate/hibernate_native_sql.htm
that show this example:
String sql = "SELECT * FROM EMPLOYEE WHERE id = :employee_id";
SQLQuery query = session.createSQLQuery(sql);
query.addEntity(Employee.class);
query.setParameter("employee_id", 10);
List results = query.list();
that, from what I have understand (correct me if I am doing wrong assertion), involves the use of an Employee model class. So th prvious query first define the query (using the :param_name syntax for the parameter), then create an SQLQuery Hibernate object, add the class used for the result, set the previous parameter neam and finally obtain a List (that I think Hibernate create as something like an ArrayList) with the retrieved object.
My problem is that I simply I have to obtain an integer value (because I have a SELECT count(*), so I will obtain an integer value and not a set of rows).
So how can I correctly use the Hibernate Native SQL to implement my SQL query into my Hibernate repository class?
Use SQLQuery.uniqueResult to retrieve a single value from the query:
String sql = "SELECT count(*) ...";
SQLQuery query = session.createSQLQuery(sql);
// set parameters...
int count = ((Number)query.uniqueResult()).intValue();
I want to use spring-batch for retrieving and processing data from a postgres db.
I have a working SQL statement that would give me the full result set (about 400k entries):
private static final String QUERY = "SELECT * FROM MyDataTable ";
Now I want to use the JpaPagingItemReader so that the data is fetched (and written elsewhere) in chunks:
JpaPagingItemReader<MyEntity> reader = new JpaPagingItemReader<>();
reader.setEntityManagerFactory(emf);
reader.setQueryString(QUERY);
But it does not work:
[] 2014-09-17 16:31:58,234 ERROR : QuerySyntaxException: unexpected token: * near line 1, column 8 [SELECT * FROM my_data_table]
I also tried SELECT FROM MyDataTable and SELECT m FROM MyDataTable m without the star. Same result.
So, how can I execute that hql query with spring-batch?
By the way: the query works fine in a sql editor like pgAdmin.
SELECT m FROM MyDataTable m is almost correct (it is valid JPQL query as long as you have entity calles MyDataTable). So, it seems that you don't have entity class named MyDataTable.
As JpaPagingItemReader#setQueryString(String) accepts JPQL queries you should make sure that you have entity class for this table and then you should use its name instead MyDataTable.
By the way - for HQL queries there's HibernatePagingItemReader.
Hi I´m using Eclipselink and I did a native query to select some fields of 2 tables. I mapped my table Logins in a model class. I would not like to map my table "B" because I need only 2 fields of this table on my sql result.. can I map this 2 fields in my Logins table to my sql result ?
My sql is this:
select l.login_id, s.lugarcerto,s.vrum, l.username, l.first_name, l.last_name, l.phone, l.fax_number, l.address, l.zip,
l.address2 as 'birth_date', l.city as 'cpf_cnpj'
from Logins l
join (select se.login_id, lugarcerto = min(case when se.service = 'IM' then '1' end), vrum = min(case when se.service = 'VE' then '1' end)
from (select distinct ad.login_id, substring(ap.Rate_code,(CHARINDEX('-', ap.Rate_code)+1),2) as 'service'
from Ad_Data.dbo.ad ad
join Ad_Data.dbo.ad_pub ap on (ad.ad_id = ap.ad_id)
where ap.ad_type =1) se
group by se.login_id) s on (s.login_id = l.login_id)
I did map Logins table and I want to map s.lugarcerto and s.vrum to my SQL query result.
There´s anyway to just add it to my Logins model ?
Not without having mappings for the attributes you want those values put into, and not without causing problems with them being cached in the entity.
Why not just return the values beside the entity, much like you would with a JPQL query such as: "Select l, subquery1, subquery2 from Logins l" ie:
Query q = em.createNativeQuery(yourQueryString, "resultMappingName");
And in the entity, include the annotation:
#SqlResultSetMapping(name="resultMappingName",
entities={#EntityResult(entityClass=com.acme.Logins.class, )},
columns={#ColumnResult(name="LUGARCERTO"), #ColumnResult(name="VRUM")}
)
Best Regards,
Chris