What is difference between hql and criteria in hibernate

Notify me of new posts via email. Criteria queries are ideal for dynamic queries. It is very simple to add restrictions and ordering as well as pagination. HQL is ideal for static queries especially if you are using named queries as they underlying SQL is generated when your session factory starts.

There is a difference in terms of performance between HQL and criteriaQuery, every time you fire a query using a criteria query, it creates a new alias for the table name which does not reflect in the last queried cache for any DB. This leads to an overhead of compiling the generated SQL, taking more time to execute, but not as much as you may think. Olida Cartulho Professional.

What is the criteria in hibernate? The Criteria interface provides methods to apply criteria such as retreiving all the records of table whose salary is greater than etc. Ruthe Ostler Professional. What is the difference between HQL and Criteria in hibernate? Bart Handirov Professional. Which is faster JDBC or hibernate? Server customisation, partitioning and so on can mitigate this though. Scalability: If an application is not likely to grow beyond a small number of database tables, then native JDBC should be adequate.

Dion Hatebur Explainer. Why we use hibernate? Hibernate reduces lines of code by maintaining object-table mapping itself and returns result to application in form of Java objects. It relieves programmer from manual handling of persistent data, hence reducing the development time and maintenance cost. Malek Encuentra Explainer. What is HQL in Java?

HQL is an object-oriented query language, similar to SQL, but instead of operating on tables and columns, HQL works with persistent objects and their properties.

Earlean Luyando Explainer. Should I use hibernate? Hibernate implements the JPA specification and so it makes it very easy for you to work with a relational database.

Blaise Yandiola Pundit. JDBC is a low level standard for interaction with databases. Guobin Krugh Pundit. Is hibernate still used? The persistence tier of most applications is not that complex. It uses a relational database with a static domain model and requires a lot of CRUD operations. Romaisaa Bernhardts Pundit. What is ORM framework? In a nutshell, an ORM framework is written in an object oriented language like PHP, Java, C etc… and it is designed to virtually wrap around a relational database.

It also includes projection and aggregation methods, including count. The Criteria API allows you to build up a criteria query object programmatically; the org. Criteria interface defines the available methods for one of these objects. The Hibernate Session interface contains several overloaded createCriteria methods.

The simplest example of a criteria query is one with no optional parameters or restrictions—the criteria query will simply return every object that corresponds to the class. Moving on from this simple criteria example, we will add constraints to our criteria queries so we can whittle down the result set. You may add these restrictions to a Criteria object with the add method.

The add method takes an org. Criterion object that represents an individual restriction. You can have more than one restriction for a criteria query. Instead of searching for exact matches, we can retrieve all objects that have a property matching part of a given pattern.

The ilike method is case-insensitive. Above example uses an org. MatchMode object to specify how to match the specified value to the stored data. The MatchMode object a type-safe enumeration has four different matches:. The isNull and isNotNull restrictions allow you to do a search for objects that have or do not have null property values.

Several of the restrictions are useful for doing math comparisons. The greater-than comparison is gt , the greater-than-or-equal-to comparison is ge , the less-than comparison is lt , and the less-than-or-equal-to comparison is le.

Moving on, we can start to do more complicated queries with the Criteria API. When we add more than one constraint to a criteria query, it is interpreted as an AND, like so:. If we want to have two restrictions that return objects that satisfy either or both of the restrictions, we need to use the or method on the Restrictions class, as follows:. The orExp logical expression that we have created here will be treated like any other criterion.

We can therefore add another restriction to the criteria:. Disjunction object to represent a disjunction. You can obtain this object from the disjunction factory method on the Restrictions class. The disjunction is more convenient than building a tree of OR expressions in code.

To represent an AND expression with more than two criteria, you can use the conjunction method, although you can easily just add those to the Criteria object. The conjunction can be more convenient than building a tree of AND expressions in code.

Here is an example that uses the disjunction:. One common application pattern that criteria can address is pagination through the result set of a database query. There are two methods on the Criteria interface for paging, just as there are for Query: setFirstResult and setMaxResults.

The setFirstResult method takes an integer that represents the first row in your result set, starting with row 0. You can tell Hibernate to retrieve a fixed number of objects with the setMaxResults method.

Using both of these together, we can construct a paging component in our web or Swing application. As you can see, this makes paging through the result set easy. You can increase the first result you return for example, from 1, to 21, to 41, etc. Sometimes you know you are going to return only zero or one object from a given query.

This could be because you are calculating an aggregate or because your restrictions naturally lead to a unique result. If you want obtain a single Object reference instead of a List, the uniqueResult method on the Criteria object returns an object or null. If there is more than one result, the uniqueResult method throws a HibernateException. The following short example demonstrates having a result set that would have included more than one result, except that it was limited with the setMaxResults method:.

Again, please note that you need to make sure that your query returns only one or zero results if you use the uniqueResult method. If you would like to work with distinct results from a criteria query, Hibernate provides a result transformer for distinct entities, org.

The Criteria API provides the org.