Jpa Subquery Join


Specification: Subquery< ActivationScenario > activationScenariosQuery Sign up for free to join this conversation. Beyond that it activates persistence exception translation for all beans annotated with @Repository to let exceptions being thrown by the JPA presistence providers be converted into Spring's DataAccessException hierarchy. 0 JPQL does not define a cast operation (JPA 2. EclipseLink is the open source Eclipse Persistence Services Project from the Eclipse Foundation. Replaces the previous specified grouping expressions, if any. If we modify query like this it works well and returns right resultset:. Your mapping says that the ID of profile is also a join column (i. Such Java objects are called JPA entities or just entities. Asking for help, clarification, or responding to other answers. The system property org. Problem with jpa criteria query multiselect. First is string argument that have to be concatenate, second is starting index and third is length of string. Summary: in this tutorial, we will show you how to work with PostgreSQL JSON data type. 그러므로 jpql에서는 cross join으로 외부 조인을 사용할 수 없다. Learn how to easily create dynamic native queries and learn how to call native SQL queries with JPA. ListJoin The ListJoin interface is the type of the result of joining to a collection over an association or element collection that has been specified as a java. JPA教程 - JPA 查询Exists示例如果子查询返回任何行,则EXISTS条件返回true。 以下代码显示如何在JPQL中使用带有子查询的EXISTS运算符。 List l = em. I'm using Glassfish Server v3. Knowing about a subquery versus inner join can help you with interview questions and performance issues. You have to increase your heap memory. The core problem is that JPA does not allow subqueries in a SELECT. Je fais une application en JSF, EclipseLink, Glassfish qui dispose d'utilisateur qui peut avoir un ou plusieurs groupes. The left outer join is on a subquery, so that if there is no row or no matching condition row in the second table, the result will show null value. One side effect is that you must qualify references to nonunique column names. createQuery( "SELECT e FROM Professor e _来自Java教程,w3cschool编程狮。. This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink) and is available under the terms of the Eclipse Public License, v. Query interface is the mechanism for issuing queries in JPA. INNER JOIN is equivalent to JOIN). This makes it impossible to solve this issue in a straightforward manner like: SELECT COUNT(_user) FROM ( SELECT DISTINCT _user FROM User _user JOIN _user. criteria used by org. For example, with deep trees you'll be much faster with JDBC than with JPA, as JPA in some cases runs thousands of SQLs while actually a single JOIN would be enough. This blog post describes how we can add custom methods into a single Spring Data JPA repository. The primary query language used is the Java Persistence Query Language, or JPQL. How to implement hashCode() correctly to use it in a HashMap? I am writing a Java application in which a user can receive some messages in form of imagesThere are text messages hidden in these images, using steganographic algorithm. JPA allows usage of subqueries in WHERE or HAVING clauses. INNER JOIN: The INNER JOIN keyword selects all rows from both the tables as long as the condition satisfies. A subQuery is created from a CriteriaQuery using the subQuery operation. Create a subquery join object. In our example the expected name of the Join Table would have been companyclient. It only takes a minute to sign up. Therefore, it may need to be taken into account while writing complex sub-queries on EclipseLink. SQL RIGHT JOIN Keyword. Is it possible to do such query in JPQL, or any. They are type-safe in terms of using interfaces and classes to represent various structural parts of a query such as the query itself, or the select clause, or an order-by, etc. To create a subquery, use a single expression builder. DATA = qqq). Learn how to easily create dynamic native queries and learn how to call native SQL queries with JPA. If an entity type has parents defined, you can formulate all possible aggregate metrics using the formula base_metric_across_parents. The Entity that is the Owner of the relationship (you remember what the Owner is, yes?) is placed on the left side of the "". pdf), Text File (. Hi, I've made some changes to the JPA store to get EclipseLink fully supported. I'm using Glassfish Server v3. Hibernate JPA Joined Inheritance I have a project with a part of the data structure made with @Inheritance(strategy = InheritanceType. We can count during aggregation using GROUP BY to make distinct when needed after the select statement to show the data with counts. One thing to note though is that it needs a non - persistent object that can hold the data retrieved by multiselect() query. A correlated subquery is a query nested inside another query which uses values from the outer query. Does JPA support subqueries in the select part of the main query. QuerySyntaxException:. 0 does not support a unidirectional OneToMany relationship without a JoinTable. subquery(Class) - Creates a Subquery to be used in one of the other clauses. It only takes a minute to sign up. Search Search. Most subQuery usage restricts the subQuery to returning a single result and value, unless used with the CriteriaBuilder exists, all, any, or some operations, or with an in operation. This guide describes how to use Querydsl in combination with JPA/Hibernate. hamideh_p Jul 19, 2016 4:21 AM Hi everyone, I've got this problem where I have to use criteria query for creating. 0 and Eclipse Distribution License, v. Prior to that version, when we try to execute such a query we'll receive an exception — the same one we described in the previous section on sorting. JPA - JPQL Query Examples: To find employee with task having no supervisor use a join Query query = em. Laravel のQuery Builderを使うと、生のSQLをなるべく書かずにすませることができる。 例えば、クエリの生成するロジックが複雑な場合、文字列連結を多用しながらSQLの文法を守りながら組み立てなければならないため難しいが、Query Builderを用いることで構造を意識するだけでよくなり、最終的にSQL. Foros del Web » Programación para mayores de 30 ;) » Java » [SOLUCIONADO] Join Criteria JPA Estas en el tema de Join Criteria JPA en el foro de Java en Foros del Web. This lets you specify joins for unrelated objects at the object level. In that case, we can speed things up by rewriting the query to use a single subquery, only scanning the widgets table once: select * from users join (. A partir daí, fica mais fácil fazer uma consulta equivalente com Criteria. This makes it impossible to solve this issue in a straightforward manner like: SELECT COUNT(_user) FROM ( SELECT DISTINCT _user FROM User _user JOIN _user. As many of you know, I strongly recommend that you avoid using RIGHT OUTER JOINs, since they make your SQL code less readable and are easily rewritten as LEFT OUTER JOINs. The nature of relational database design means that we will often have related data that is stored in different tables. java Main Class: JPASubStringFunction. As seen above, just like CriteriaQuery, Subquery also has select, restriction, join etc methods. literal(1L) in complex sub-query statements on EclipseLink, EclipseLink gets confused and causes an exception. roles _role WHERE _role. Such Java objects are called JPA entities or just entities. I have trouble to translate some easy SQL statement to JPQL, because of a used subquery, which is not supported by JPQL. In our example the expected name of the Join Table would have been companyclient. FROM Clause. This tutorial has already taught us how we can create static database queries with Spring Data JPA. Single Row Subqueries. their semantics are different. List l = em. function Class and Description. Then I mapped the entities to the views using classing Hibernate/JPA mappings. phones is a path expression that traverses phone numbers of Teacher. answer_numeric) FROM `answers` divisor INNER JOIN `answers` dividend WHERE divisor. These examples are extracted from open source projects. 3, "Creating repository instances". Tuning SQL with "rownum" filters Oracle Database Tips by Donald BurlesonJuly 24, 2015 Many people forget that the Oracle SQL optimizer is an in-house computer program, written by software engineers, and it's not something where the rules of scientific endeavor apply. JPA - QueryDSL, JPQL Query Builder Class 이전 포스팅에서 다뤘던 JPA Criteria는 문자가 아닌 코드로 JPQL을 작성하도록 도와주는 쿼리빌더였기 때문에 문법 오류를 컴파일 단계에서 잡을 수 있고 IDE툴을 이용. Ways to join data from more than one table When you want to see information from multiple tables, you can use a SELECT statement. I'm using the JPA Query Language for the first time and have run into a problem. Deprecated since 1. This blog post describes the last method. JPA and Hibernate versions older than 5. SQL is an "old", yet established and well-understood technology. In EclipseLink, you can specify a query hint to perform nested join fetches. java Main Class: JPASubStringFunction. As this query needs two levels of grouping, maybe it can't be expressed with JPQL / Querydsl JPA. This keyword will create the result-set by combining all rows from both the tables where the condition satisfies i. accessTime F Subqueries in JPA is not working with OpenJPA (Object Relational Mapping forum at Coderanch). createQuery( "SELECT e FROM Professor e _来自Java教程,w3cschool编程狮。. Because this is a recurrent question, I decided to write a blog post in which I describe this mapping is more detail. JPQL allows subqueries to refer to a relation based on a join alias of the outer query within the from clause, also known as correlated join. The syntax of the Java Persistence Query Language (JPQL) is very similar to the syntax of SQL. The JPA spec only defines a Left Outer Join. The left outer join is on a subquery, so that if there is no row or no matching condition row in the second table, the result will show null value. 1 draft, and is supported in EclipseLink 2. It is used to create queries against entities to store in a relational database. Consider we have a model as shown in the diagram We would like to select the phones of a teacher with first name as “prasad” using joins. JPA subquery não funciona up 1 down não estou conseguindo filtrar a subquery, com o JPA, todos os elemento retornam (como se a subquery não estivesse ali). If it's not in JPQL, I don't expect it from JPASubQuery then. The implementation of this Spring JPA Tutorial can be found in the GitHub project – this is a Maven-based project, so it should be easy to import and run as it is. Then I mapped the entities to the views using classing Hibernate/JPA mappings. Most subQuery usage restricts the subQuery to returning a single result and value, unless used with the CriteriaBuilder exists, all, any, or some operations, or with an in operation. [JPA]객체지향쿼리 - JPQL(count, max, min, avg, sum, group by, having, order by, join) 노랭이가 2016. The result is NULL from the left side, when there is no match. 1 **主表 MasterEntity @OneToOne @JoinColumn(name = "masterext") MasterExtendEntity masterExtendEntity; //关联表. As you can see, I define the subquery in the same way as I create a CriteriaQuery. Hibernate subquery detachedCriteria Vlad Mihalcea already answered the use in HQL. Below are the some of the features of the subquery. Provide details and share your research! But avoid …. Persistence bottom I just announced the new Learn Spring course, focused on the fundamentals of Spring 5 and Spring Boot 2:. From what I tried, JPQL does not seems to accept subquery on outer join. Knowing about a subquery versus inner join can help you with interview questions and performance issues. Following methods of Subquery allows to correlate the subquery with the parent query:. Are Criteria Subqueries and Joins now working in 3. For example, you can open two instances of MVC group Laporan (report), each displaying different report. The following code is from Professor. However, your application code must perform additional queries to fetch referenced documents. Join the tables. Hibernate subquery join using Criteria I recently needed to create max query in hibernate returning an object instead of the maximal value of the field and I wanted to do this using Hibernate Criteria in our JPA environment. If the flag is off , the optimizer chooses subquery materialization over IN -to- EXISTS subquery transformation. We're using JPA with hibernate as the provider, we have a query that contains a join with a subquery in the FROM clause, but we get the following error: org. Hibernate subquery detachedCriteria Vlad Mihalcea already answered the use in HQL. It is the most common type of join. It not only enables us to write queries without doing raw SQL, but also gives us some Object Oriented control over the queries, which is one of the main features of Hibernate. This article explains how to join three tables in Single SQL Query which will work in MySQL, SQL Server and Oracle database. Subqueries in hibernate can be referred as the queries that are surrounded by parentheses (). As part of the complete overhaul of the Enterprise JavaBeans (EJB) specification, database persistence was broken out into a completely separate specification, the Java Persistence API (JPA). 1 require a defined relationship to join two entities in a JPQL query. Get multiple columns from a select subquery. Jpa Subquery - student. 1 draft, and is supported in EclipseLink 2. Read completely JPA 2. Beyond that it activates persistence exception translation for all beans annotated with @Repository to let exceptions being thrown by the JPA presistence providers be converted into Spring's DataAccessException hierarchy. [NOT] EXISTS operator gives best performance when the subquery i. This means that the JPQL user is normally free from having to know how every relationship is joined. jOOQ's reason for being - compared to JPA. driven query contains huge volume of data. - infobip/infobip-spring-data-jpa-querydsl. If non is configured we will derive the count query from the method name. This can be done indirectly however, if you add a secondary join to the subclass to the query. It is also no longer correlated to the outer query, so the finished counts may not meet your expectations. childEntities c JOIN p. Of course, these examples use the table and the entity described in " Examples using JPA 2. - gist:5292986. Questions: I tried to convert a native query to criteria builder query I. If no grouping expressions are specified, any previously added grouping expressions are simply removed. Some examples of the criteria API (JPA 2. The Java Persistence query language is an extension of the Enterprise JavaBeans query language, EJB QL, adding operations such as bulk deletes and updates, join operations, aggregates, projections, and subqueries. createQuery( "SELECT m FROM Professor m WHERE (SELECT COUNT(e) "+ "FROM Professor e WHERE e. The result should be the employees whose job details exists in JobInfo table. 1 require a defined relationship to join two entities in a JPQL query. The only solution I have seen is. I'm using Glassfish Server v3. Multiple Column Subquery ,alt sorgu sonucu birden fazla alan/deger /kolon (column) donmesine izin verir. 4 The above solution for native queries works fine for Spring Data JPA version 2. Every valid criteria API expression can be used as selection, because all the criteria API expressions are represented by a sub interface of Selection - Expression javax. But your table definition shows that you have a userId column in profile to reference the profile's user ID. Second, gets the result and passes it to the outer query. Welcome to Reddit, So I could do something like this: SELECT avg (dividend. JPQL is developed based on SQL syntax. simple-jpa 0. Change existing data model to use embedded documents to embed related data in a single document. ownerId o WHERE c. Third, executes the outer query. The result is NULL from the left side, when there is no match. 0 introduces a number of JPQL updates. Accelebrate's JPA 2 Training: Introduction to the Java™ Persistence API 2 class teaches attendees how to implement JPA for data persistence. My one test result on an Intel processor shows that JPA queries are 15% faster than. 2, is a Java specification that is a common ground for most Java ORMs. Here subquery. 1 draft, and is supported in EclipseLink 2. Luckily, this example can be fixed as follows:. 5 (also referred to as "Java 5") or higher, as it makes heavy use of new Java language features such as annotations and generics. What is the difference between a subquery and inner join? In this puzzle, we’re going to learn how to rewrite a subquery using inner joins. Note that starting from Oracle 12c you can also use FETCH FIRST clause in Oracle, so the conversion is not required. Let's say you have an entity called Product and an entity called ProductOwner and there is a 1 to n relationship from ProductOwner to Product but you can only access Product from ProductOwner. Use a Complete Subquery when you don’t have indexes. persistence. 0 JPQL does not define a cast operation (JPA 2. One thing to note though is that it needs a non - persistent object that can hold the data retrieved by multiselect() query. The system property org. Scribd is the world's largest social reading and publishing site. It seems that the QueryDslPredicateExecutor expects only single table predicates. hamideh_p Jul 19, 2016 4:21 AM Hi everyone, I've got this problem where I have to use criteria query for creating. class); Root d = q. Since the subquery always produces exactly one row, the number of rows output of the join is precisely equal to the number of rows in T1. JPA Filter for SQL NOT IN with subquery. in JPQL, subqueries are only allowed in the WHERE and HAVING part. This tutorial has now covered two of the three methods which we can use to create query methods with Spring Data JPA. We saw how querying on associations or selecting data inside associations may result in implicit join queries. Here the parameter expression is simply a string value prefixed with a semi-colon. SQL subquery is usually added in the WHERE Clause of the SQL statement. JPA and Hibernate versions older than 5. If your JPA provider has support for JPA 2. Eg, report all of A, and where A has made a specific kind of B, report the name of that B. Getting Started with JPA - DZone - Refcardz Over a million developers have. groupBy: Add group by arguments in varargs form. Does JPA support subqueries in the select part of the main query. The following code is from Professor. Without CONNECTION_ADMIN or SUPER, you can kill only your own threads and statements. In this tutorial, we'll discuss a very useful JPA feature – Criteria Queries. Spring Data JPA Specification Criteria Query generally used for search functionality on a page where users want to search by giving some inputs or by selecting several dropdown values. A query for persistent Java objects is typesafe if a compiler can verify it for syntactic correctness. Both these tables are owned by the SCOTT user, together with two less frequently used tables: BONUS and SALGRADE. Re: [JPA] How to avoid excessive joins in queries on InheritanceType. JPA 2 is a standard feature of Java EE 6 and later, but can also be used with Java SE applications. Following methods of Subquery allows to correlate the subquery with the parent query:. comps as comp where. Persistence bottom I just announced the new Learn Spring course, focused on the fundamentals of Spring 5 and Spring Boot 2:. Can someone give me a hint, how to achieve the same result with JPQL or JPA2. I soon found out that I couldn't use inner joins on a delete statement, even at the SQL level. If no grouping expressions are specified, any previously added grouping expressions are simply removed. Java: Using the specification pattern with JPA This article is an introduction to using the specification pattern in Java. createQuery("SELECT e FROM Employee e WHERE (SELECT COUNT(p) FROM e. Subqueries To create a subquery you create a com. This means that the JPQL user is normally free from having to know how every relationship is joined. Get single records when duplicate records exist. 4 The above solution for native queries works fine for Spring Data JPA version 2. The ON clause is defined in the JPA 2. In this section we will discuss how to write subqueries using Detached Criteria in Hibernate. Table of Contents1. criteria used by org. In some cases (till 10. Suppose you want to know the rental information of customer id 1 and 2, you can use the IN operator in the WHERE clause as follows:. The join lambda is not limited to only returning navigational queries but can also be used for cross-joins with arbitrary entity streams. getResultList(); Example. I first set the Book entity as the root and join it with the Author entity. Get some hands-on insight on what's behind developing jOOQ. References to columns from DISTINCT queries. []string is just syntactic sugar for (in this case) [3]string. Aggregate functions like GROUPBY and HAVING clause just like SQL. Here's the query transformation: I originally had this query:. [JPA]객체지향쿼리 - JPQL(count, max, min, avg, sum, group by, having, order by, join) 노랭이가 2016. Java Persistence API (JPA) provides the specification of managing data, such as accessing and persisting data, between Java Objects and the databases. The only solution I have seen is. Workaround. JOIN keyword says the JPQL consists of an INNER JOIN (as INNER keyword is optional) t. Feel free to file an EclipseLink enhancement or request its inclusion in the JPA specification. A join to an entity, embeddable, or basic type. 1, Java EE 6 and persistence provider eclipselink. getResultList();. phones path expression. Spring Data JPA provides three different approaches for creating custom queries with query methods. We will learn to create database. Hibernate subquery detachedCriteria Vlad Mihalcea already answered the use in HQL. A subquery has an expression as its selection item. The LEFT OUTER JOIN clause lists rows from the left table even if there are no matching rows on right table. Similar to the INNER JOIN clause, the LEFT JOIN is an optional clause of the SELECT statement, which appears immediately after the FROM clause. It is also no longer correlated to the outer query, so the finished counts may not meet your expectations. subqueries when null values are retrieved • Write a subquery in a FROM clause. id IN (1) ). Gets you started with the Java Persistence API, covering the basics of JPA and preparing you to write JPA applications. It is set to TRUE, if at least one record is found in the subquery correlating with the main driving query, and stops further scanning of the table. The correlated subqueries in Spark SQL are rewritten to the queries where the subquery is joined to the outer one with the left outer join. Re: Using Subqueries in Toplink Donald Smith-Oracle Mar 12, 2003 6:44 PM ( in response to 35888 ) I'm not sure I follow the example. JPQL is syntactically very similar to SQL, but is object-oriented rather than table-oriented. More Apress Books Reviews … In these days for an Enterprise for its application is mandatory has a mechanism of persistence and easy way to access them, JPA 2. It happens independently on the subquery location. projects p"). Test your JPA knowledge by answering these tricky interview questions on Java Persistence API. Range Variable Declarations. subquery(Class) - Creates a Subquery to be used in one of the other clauses. 1, Jinq also support a variant of leftOuterJoin() that passes a stream source to the join lambda. Does JPA support subqueries in the select part of the main query. The implementation of this Spring JPA Tutorial can be found in the GitHub project - this is a Maven-based project, so it should be easy to import and run as it is. Joining multiple tables in SQL is always a tricky task, It can be more difficult if you need to join more than two tables in single SQL query, worry not. In Java EE, the Java Persistence API (JPA) is the standard API for accessing relational databases, providing a simple and efficient way for managing the object/relational mapping (ORM) of regular Java objects (POJO) to relational data. getResultList(); Example. 0) When I wrote my examples on how to use JavaFX and JPA 2. SQL Subquery in the SELECT clause A subquery can be used anywhere an expression can be used in the SELECT clause. For example, with deep trees you'll be much faster with JDBC than with JPA, as JPA in some cases runs thousands of SQLs while actually a single JOIN would be enough. JPQL provides an additional type of identification variable, a join variable, which represent a more limited iteration over specified collections of objects. There is no need to do a table join. This means that the JPQL user is normally free from having to know how every relationship is joined. Left Joins to link three or more tables MANY-TABLE JOINS IN MYSQL - BACKGROUND Data held in SQL tables should be normalised - in other words, held in neat multiple tables with complete rows, only one piece of logical data per cell, and with information not being repeated in multiple places. Please do give a read at JPA 2 Tutorial - Relationships - Many To Many if nothing seems to make sense at this point! Let us modify the M2mSelfTest JUnit class now. Introduction It’s quite common to retrieve a root entity along with its children associations on multiple levels. Let's say you have an entity called Product and an entity called ProductOwner and there is a 1 to n relationship from ProductOwner to Product but you can only access Product from ProductOwner. Because this is a recurrent question, I decided to write a blog post in which I describe this mapping is more detail. A subquery can return zero or more rows. A query for persistent Java objects is typesafe if a compiler can verify it for syntactic correctness. childEntities c JOIN p. Maintaining a historical view of database records has been a problem that has been solved before but not easily. You will have to break things up into two queries from your application code. INNER JOIN queries select the records common to the target tables. The Subquery interface defines functionality that is specific to subqueries. With parallel selects, use multiple expression builders when you define a single query. e value of the common field will be same. SQLSubQuery instance, define the query parameters via from, where etc and use unique or list to create a subquery, which is just a type-safe Querydsl expression for the query. You can display more than one instances of the same MVCGroup. name = :project) 使用EclipseLink + H2数据库,我无法获得本书的JPQL和相应的标准。. Such Java objects are called JPA entities or just entities. JPQL is Java Persistence Query Language defined in JPA specification. Are Criteria Subqueries and Joins now working in 3. You can specify it between the SELECT keyword and the selection list to have a global effect on all cross joins in the statement, or you can specify it in the FROM clause. Using subqueries in the join clause is not allowed. Prior Oracle 12c you can use the ROWNUM pseudo-column to limit the number of retrieved rows, but it is applied before sorting, so you have to use a sub-query in order to limit the number of rows after sorting. Is it possible to do such query in JPQL, or any. Similar to the INNER JOIN clause, the LEFT JOIN is an optional clause of the SELECT statement, which appears immediately after the FROM clause. INNER JOIN queries select the records common to the target tables. addAttribute is an API related to parameterizing arguments for reusing queries. Unidirectional OneToMany, No Inverse ManyToOne, No Join Table (JPA 2. In addition, we will introduce you to some of the most common PostgreSQL JSON operators and functions for handling JSON data. from(Department. getResultList();. JPA - QueryDSL, JPQL Query Builder Class 이전 포스팅에서 다뤘던 JPA Criteria는 문자가 아닌 코드로 JPQL을 작성하도록 도와주는 쿼리빌더였기 때문에 문법 오류를 컴파일 단계에서 잡을 수 있고 IDE툴을 이용. Second, gets the result and passes it to the outer query. A fetch join has the same join semantics as the corresponding inner or outer join, except that the related objects specified on the right-hand side of the join operation are not returned in the query result or otherwise referenced in the query. timestamp = maxtime. It doesn't require a join here nor I mentioned one though it produces two superfluous joins which are completely unnecessary. A join performed with STRAIGHT_JOIN is like a cross join but forces the tables to be joined in the order named in the FROM clause. If you have faced any interesting SQL query or you have any problem and searching for the. in JPQL, subqueries are only allowed in the WHERE and HAVING part. We will pass in the query string to be executed in underlying database and the entity type that will be returned as result. JPA 2 is a standard feature of Java EE 6 and later, but can also be used with Java SE applications. springframework. 0 Criteria Query/Builder DELETE : Typesafe JPQL Select the Latest record date for each User a. persistence. I need to create subquery with two custom field, but subquery doesn't have multiselect method and select method has Expression input parameter(In query this is Selection) and constact method not suitable. getResultList();. JPA - QueryDSL, JPQL Query Builder Class 이전 포스팅에서 다뤘던 JPA Criteria는 문자가 아닌 코드로 JPQL을 작성하도록 도와주는 쿼리빌더였기 때문에 문법 오류를 컴파일 단계에서 잡을 수 있고 IDE툴을 이용. If no grouping expressions are specified, any previously added grouping expressions are simply removed. 4) we would have to hint the sub-query with NO_UNNEST to avoid the hash join semi. Multiple-Column Subqueries. A query for persistent Java objects is typesafe if a compiler can verify it for syntactic correctness. The key to making this work using the criteria API is to understand the difference between Root#get() and Root#join(). the query above returns an int which is the price of the magazine.