How to Implement GROUP BY Clause in Hibernate Using Criteria API?

Implementing Group by Criteria Object in Hibernate

In Hibernate, Criteria API allows you to construct complex queries and retrieve data from the database using object-oriented criteria. To implement a SQL query using the Criteria API, you need to use the createCriteria() method in the Hibernate session.

For a SQL query like:

SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name <operator> value
GROUP BY column_name

You can use the groupProperty() method of the CriteriaQuery class to group the results by the specified column. You can also use the aggregate functions provided by the Projections class to perform the desired aggregate operations.

Here is an example of how you can implement this query using Hibernate Criteria:

CriteriaQuery<Tuple> criteriaQuery = session.getCriteriaBuilder().createTupleQuery();
Root<SomeTable> root = criteriaQuery.from(SomeTable.class);

criteriaQuery.multiselect(
    root.get("column_name"),
    Projections.max(root.<Double>get("column_name")),
    Projections.min(root.<Double>get("column_name")),
    Projections.count(root.get("column_name"))
);

criteriaQuery.where(
    session.getCriteriaBuilder().ge(root.<Double>get("column_name"), value)
);

criteriaQuery.groupBy(root.get("column_name"));

List<Tuple> result = session.createQuery(criteriaQuery).getResultList();

This criteria query will return a list of tuples containing the column_name, its maximum value, minimum value, and count, grouped by the column_name. Note that the type of aggregate function depends on the type of the column you are aggregating on.

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