How to Implement GROUP BY Clauses with Hibernate Criteria?

Implementing Group By Criteria in Hibernate

Hibernate's Criteria API provides a powerful way to construct database queries. This article demonstrates how to use Criteria to implement a SQL query with GROUP BY and aggregate functions.

SQL Query

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

Criteria Implementation

Criteria criteria = session.createCriteria(SomeTable.class);
criteria.add(Restrictions.lt("someColumn", value));
criteria.setProjection(Projections.projectionList()
        .add(Projections.groupProperty("someColumn"))
        .add(Projections.max("someColumn"))
        .add(Projections.min("someColumn"))
        .add(Projections.count("someColumn")));

Key Points

• Use groupProperty() to specify the column to group by.
• Use Projections class to create aggregate functions, such as max(), min(), and count().
• The setProjection() method sets the projection for the query, specifying which columns and aggregate functions to include in the result.

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