How to generate "select count(*) ..." using CriteriaQuery - java

I wrote the following code to get the count of "ExampleEntity":
cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Long> cq = cb.createQuery(Long.class);
root = cq.from(ExampleEntity);
cq.select(cb.count(root));
return entityManager.createQuery(cq).getSingleResult();
Generated sql:
Hibernate: select count(exampleen0_.id) as col_0_0_ from EXAMPLEENTITY exampleen0_
But, for performance reasons (using a Oracle 11g database),I need to generate the following sql:
Desired sql: select count(*) as col_0_0_ from EXAMPLEENTITY exampleen0_
It's quite simple to do creating JPQL queries, but I would have to rewrite a lot of existing code for filters.
How can I generate "count(*)" instead of "count(exampleen0_.id)" using CriteriaQuery?

It's extremely hard to force the hand of the SQL generated by Hibernate. Instead, I would consider writing a native query.
Query query = entityManager.createNativeQuery(
"SELECT COUNT(*) FROM EXAMPLEENTITY", Long.class);
return query.getSingleResult();
Note: Native queries can get messy when using more complex logic, but this particular one complies to the ANSI standard and should run without issue against any commonly used DB without having to worry about any db-specific syntax issues.

It works in Oracle...
BigDecimal count = (BigDecimal) manager.createNativeQuery(query).getSingleResult();

Related

Avoid SQL Injection in Spring JPA

I am using sql query like
String query = "Select max(case when UPPER(key)='firstname' then value end) as firstNameName, , ... order by "+orderBy;
result = em.createNativeQuery(query).getResultList();
em.close();
for some reason i would have to use dynamic +orderBy . Where orderBy =firstname ASC , lastname DESC etc. Tried using .setParameter(1, orderedBy) but in this case i am not getting expected ordered results.
For avoiding sql injection threats you firstly need to remove appending parameters to your query. When you're appending parameters in your app, the atacker can hijack your sql code (with apostrophes and other means for example)
For example:
If your query is "select * from table where name="+id
The attacker can pass to the field values such as:
'John' or 1=1; ->sees all your records in this table
Or even
'John' or 1=1;Delete all from users;' -> deleting all entries from users table.
Hijacking queries can be avoided via mechanisms such as input sanitization, input whitelisting/blacklisting(removing unwanted characters from the input/ defining a list of allowed or unnalowed characters). Most modern framerowks such as JDBC/JPA/Hibernate can offer protection from this threat.
With all this stated we should take into consideration the following scenarios:
Considering sql where parameters:
JDBC for example offers prepared statements, where you define a variable in your sql, and the framework replaces it
In your case a JPA implementation(Hibernate) also has mechanisms for avoiding this threat, also via parameterized queries and positional paramaters:
via native query positional parameters:
Query q = em.createNativeQuery("SELECT count(*) FROM mytable where username = ?1");
q.setParameter(1, "test");
via named parameters(jplq)
Query q = em.createQuery("SELECT count(*) FROM mytable where username = :username");
q.setParameter("username", "test");
Considering orderBy parameters:
CriteriaQuery/spring Specifications
CriteriaBuilder cb = this.entityManager
.getCriteriaBuilder();
CriteriaQuery<RESULT> criteria = cb.createQuery(RESULT.class);
Root<RESULT> root = criteria.from(RESULT.class);
return this.entityManager.createQuery(
criteria.select(root).orderBy(cb.asc(root.get("ORDER_BY_FIELD"))))
.getResultList();
More on criteriaQueries usage and config here
Passing orderBy via spring specific Sort parameter built beforehand(using the spring-data library)
Sort sort = Sort.by(Sort.Direction.ASC, "criteria");
em.createQuery(QueryUtils.applySorting(yourSqlQuery_withoutSorting,sort));
annotate method with #Query with spring-data library:
You can achieve the same result with less boiler plate code(without injecting an entityManager and creating a nativeQuery) by just annotating a method with a #Query annotation:
#Query("select u from User u where u.lastname like ?1%")
List<User> findByAndSort(String lastname, Sort sort);
Note:
Native vs non-native(jpql):
JOQL queries are independent of the database vendor(MySQL,PostGres,Oracle,DB2), nativeQueries usages are more focused when you need to use a database specific functionalities which differes accross vendors.
For a brief example jpql can not support native [With]2 clause PLSQL standard functions
Regarding your edit:
You can try to apply the following sql trick for dynamic ordering:
SELECT param1, param2 ...
FROM ...
ORDER BY case when :sortParam='name asc' then name asc END
case when :sortParam='name desc' then name desc END
....
else 0

Criteria API and JPA2 GroupBy issue with date

I am writing a query to find dates and their counts for that particular date from my entity table, and running into an issue with the groupBy statement.
Here is my criteria API calls:
CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
CriteriaQuery<Tuple> criteriaQuery = criteriaBuilder.createTupleQuery();
Root<HtEntity> from = criteriaQuery.from(entityClassType);
Expression<String> log_date = criteriaBuilder.function("TO_CHAR",
String.class, from.get(Constants.PARAM_DATE), criteriaBuilder.literal("yyyy-MM-dd")
);
//create the select statement
criteriaQuery.select(
criteriaBuilder.tuple(
log_date.alias("log_date"),
criteriaBuilder.count(from)));
criteriaQuery.groupBy(log_date); //ISSUE HERE!!!
TypedQuery<Tuple> query = em.createQuery(criteriaQuery);
List<Tuple> results = query.getResultList();
Without trying to cast the date column with to_char and using just the date column it works, but obviously is not aggregated as I want to. I want just the date in yyyy-MM-dd and not the entire timestamp, and I can only see doing this by using groupBy which causes an error
"org.hibernate.exception.SQLGrammarException: could not extract
ResultSet"
And there is the query string that is build found from my debugger:
select function('TO_CHAR', generatedAlias0.date, :param0), count(generatedAlias0) from LogMessageEntity as generatedAlias0 group by function('TO_CHAR', generatedAlias0.date, :param1)
Please let me know what I am doing wrong. The corresponding Postgres SQL query should be working for this, as I can test it and see that it would work.
CriteriaApi has a good way of providing me with a headache, but I did end up finding a solution to this a while back, providing the answer for future curious folks:
CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
CriteriaQuery<Object[]> criteriaQuery = criteriaBuilder.createQuery(Object[].class);
Root<MyEntity> from = criteriaQuery.from(classType);
criteriaQuery.multiselect(
from.get("date").as(java.sql.Date.class),
criteriaBuilder.count(from)
);
/*Add order by and group by clause*/
criteriaQuery.orderBy(criteriaBuilder.desc(from.get("date").as(java.sql.Date.class)));
criteriaQuery.groupBy(from.get("date").as(java.sql.Date.class));
TypedQuery<Object[]> query = em.createQuery(criteriaQuery);
List<Object[]> results = query.getResultList();
You will notice that I am casting the column projecting in my multi-select statement, and my groupBy as a java.sql.Date type. CriteriaApi has a strict type-safe format such that you cannot mix types for the groupBy and the select statement if you are aggregating on that specific column. My issue was that I was selecting on the date column with a function call, and also trying to apply that to the groupBy.
While the generated query statement works via command line, it does not work for the CriteriaApi. The reason it cannot generate a ResultSet is due to it assuming the projection and aggregation in the groupBy are not the same type (I think) and therefore, if you need to use a function on a column in your select statement and also aggregate on that column you need to either think of a way you can avoid using the function (which is what I did), or generate a native query with the Hibernate EntityManager object you have.
It is unfortunate, but I believe CriteriaApi has a number of limitations with this being one of them. It should probably be submit to their team as a bug, but I'm not sure where to do this.
Old question, but the issue is still relevant. I've tried your solution, but it didn't work for me. What did work is the trunc function, instead of the to_char:
Path<FeedbackType> feedbackTypePath = itemRoot.get("feedbackType");
final Expression date = criteriaBuilder.function("trunc", java.sql.Date.class, votesJoin.get("creationDate"));
selects.add(feedbackTypePath);
selects.add(date);
selects.add(criteriaBuilder.count(itemRoot.get("id")));
criteriaQuery.multiselect(selects);
criteriaQuery.where(criteriaBuilder.equal(votesJoin.get("creationDate"), oldestVoteSubquery));
criteriaQuery.groupBy(feedbackTypePath, date);
It looks like the criteriabuilder does not like the literal in the groupBy.

JPQL query containing LIKE converted into criteria

I need to use the LIKE operator into an JPA query. I need to use it for types other then String but the JPA criteria API allows me to add only String parameters. I tried using the .as(String.class) but something fails and also tried calling the CAST function from the underlying Oracle that again fails for unknown reasons to me.
I tried writing the query also in JPQL and it works as expected. This is the query:
SELECT p from CustomerOrder p where p.id like '%62%'
UPDATE:
The query must be built in a generic fashion as it is for filtering, so it needs to be created at runtime. On the query that is already created I tried to add the LIKE clause like this:
query.where(builder.like(selectAttributePath.as(String.class), "%"+filterValue.toString().toLowerCase()+"%"));
But this crashes with this exception:
org.hibernate.hql.internal.ast.QuerySyntaxException: expecting CLOSE, found '(' near line 1, column 156 [select distinct generatedAlias0.id from de.brueckner.mms.proddetailschedact.data.CustomerOrder as generatedAlias0 where cast(generatedAlias0.id as varchar2(255 char)) like :param0]
I executed the same query directly to Oracle using SQLDeveloper, so it should be sound from this point of view. So the problem is the Hibernate is the issue. Any suggestions on how to fix it?
How can I write this query using JPA Criteria?
I fixed the problem by invoking the 'TO_CHAR' function from the underlying Oracle DB and using the LIKE operator like for normal String's.
query.where(builder.like(selectAttributePath.as(String.class), "%" +filterValue.toString().toLowerCase() + "%")
You can try the below code, it might require modifications.
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<CustomerOrder> cq = cb.createQuery(CustomerOrder.class);
Root<CustomerOrder> order = cq.from(CustomerOrder.class);
cq.where(cb.like(Long.valueOf(order.get(CustomerOrder_.id)).toString(), "%62%"));
TypedQuery<CustomerOrder> q = em.createQuery(cq);
List<CustomerOrder> results = q.getResultList();

jpa select statement with subnets

I am trying to write query with multiple select subnets in it.But I defined a nativequery
I am giving error. Compiler specifies that "(" after "from" is not proper. How can I define
a native query in JPA 2.0
For eaxmple:
SELECT *
from (SELECT ****C) REI3 where column1 != 1
GROUP BY REI3.column2 order by REI3.column3 ASC
JPA does not have too much to do with validating SQL syntax, query is passed to JDBC driver. Likely you are trying run query such a way, that it is interpreted as JP QL. Instead try following method to execute it as
Query q = em.createNativeQuery("Your SQL here");
Other alternative is to use NamedNativeQuery Example

convert sql to hql

I am performing this via sql but i want to do this in hql, select statement in from ( select count(*)...) not works in hql, any sugestion and optimization would be appreciated
SELECT u.username,u.device_tocken,sr.count
from users u,
(select count(*) as count ,ssr.recepient as res from survey_recipient ssr where
(ssr.is_read is false and ssr.recepient in ('abc','xyz'))group by ssr.recepient ) sr
where
(u.username = sr.res and u.device_tocken is not null)
Hibernate does not support subselects in from clouse.
i tried many things and gave up when i found this jira issue.
see here https://hibernate.onjira.com/browse/HHH-3356
But if you have to use subselect you can create database views and use them in your sql as normal tables.

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