add test for median()

hibernate-core/src/main/java/org/hibernate/dialect/Dialect.java

@@ -828,7 +828,11 @@ public abstract class Dialect implements ConversionContext {
 
 		CommonFunctionFactory functionFactory = new CommonFunctionFactory(queryEngine);
 
-		//aggregate functions, supported on every database
+		//standard aggregate functions count(), sum(), max(), min(), avg(),
+		//supported on every database
+
+		//Note that we don't include median() in this list, since it's difficult
+		//to implement on MySQL and Sybase ASE
 
 		functionFactory.aggregates( this, SqlAstNodeRenderingMode.DEFAULT );
 

hibernate-core/src/test/java/org/hibernate/orm/test/query/hql/FunctionTests.java

@@ -34,12 +34,14 @@ import java.sql.Timestamp;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.LocalTime;
+import java.util.List;
 import java.util.Map;
 
 import org.hamcrest.Matchers;
 
 import static org.hamcrest.CoreMatchers.*;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 /**
@@ -57,6 +59,8 @@ public class FunctionTests {
 		scope.inTransaction(
 				em -> {
 					EntityOfBasics entity = new EntityOfBasics();
+					entity.setTheInt(5);
+					entity.setTheDouble(1.0);
 					entity.setId(123);
 					entity.setTheDate( new Date( 74, 2, 25 ) );
 					entity.setTheTime( new Time( 20, 10, 8 ) );
@@ -1423,6 +1427,22 @@ public class FunctionTests {
 		);
 	}
 
+	@Test
+	@RequiresDialectFeature(feature = DialectFeatureChecks.SupportsMedian.class)
+	public void testMedian(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					List<Object[]> list = session.createQuery("select median(e.theDouble), median(e.theInt) from EntityOfBasics e", Object[].class)
+							.list();
+					assertEquals( 1, list.size() );
+					Double d = (Double) list.get(0)[0];
+					Double i = (Double) list.get(0)[1];
+					assertEquals(d,1.0, 1e-5);
+					assertEquals(i,5.0, 1e-5);
+				}
+		);
+	}
+
 	@Test
 	public void testGrouping(SessionFactoryScope scope) {
 		scope.inTransaction(

hibernate-testing/src/main/java/org/hibernate/testing/orm/junit/DialectFeatureChecks.java

@@ -26,8 +26,6 @@ import org.hibernate.dialect.TiDBDialect;
 import org.hibernate.query.sqm.FetchClauseType;
 import org.hibernate.sql.ast.spi.StringBuilderSqlAppender;
 
-import org.hibernate.testing.DialectCheck;
-
 /**
  * Container class for different implementation of the {@link DialectFeatureCheck} interface.
  *
@@ -464,7 +462,15 @@ abstract public class DialectFeatureChecks {
 			return !( dialect instanceof H2Dialect
 					|| dialect instanceof MySQLDialect
 					|| dialect instanceof SybaseDialect
-					|| dialect instanceof DerbyDialect);
+					|| dialect instanceof DerbyDialect );
+		}
+	}
+
+	public static class SupportsMedian implements DialectFeatureCheck {
+		public boolean apply(Dialect dialect) {
+			return !( dialect instanceof MySQLDialect
+					|| dialect instanceof SybaseDialect
+					|| dialect instanceof DerbyDialect );
 		}
 	}
 }