Hi I need to use Hibernate 3.1.3 to create a query that returns an object and a aggregate value like this: select max (t.test_date), t from TestTo t. Because I have an aggregate function I have to define the GROUP BY clause: select max (t.test_date), t from TestTo t group by t But I get an error: ORA-00979: not a GROUP BY expression The generated SQL is: select max(testto0_.test_date) as col_0_0_, testto0_.test_value as col_1_0_, testto0_.test_value as test1_0_, testto0_.test_date as test2_0_ from TEST testto0_ group by testto0_.test_value It seems that Hibernate is expanding all columns of the TestTo class in the SELECT statement but not in the GROUP BY statement. The TestTo class: public class TestTo { private int value; private Date date; public TestTo() { } public int getValue() { return value; } public void setValue(int value) { this.value = value; } public Date getDate() { return date; } public void setDate(Date date) { this.date = date; } } The Mapping File: <hibernate-mapping> <class name="mypackage.TestTo" table="TEST"> <id name="value" column="test_value"> <generator class="sequence"> <param name="sequence">seq_test</param> </generator> </id> <property name="date" column="test_date"/> </class> </hibernate-mapping>