make adding fractional seconds work on h2 and HSQL

Signed-off-by: Gavin King <gavin@hibernate.org>

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

@@ -4821,7 +4821,8 @@ public abstract class Dialect implements ConversionContext, TypeContributor, Fun
 	public int getDefaultTimestampPrecision() {
 		//milliseconds or microseconds is the maximum
 		//for most dialects that support explicit
-		//precision, with the exception of DB2 which
+		//precision, with the exception of Oracle,
+		//which accepts up to 9 digits, and DB2 which
 		//accepts up to 12 digits!
 		return 6; //microseconds!
 	}

hibernate-core/src/main/java/org/hibernate/dialect/H2Dialect.java

@@ -443,7 +443,11 @@ public class H2Dialect extends Dialect {
 		if ( intervalType != null ) {
 			return "(?2+?3)";
 		}
-		return "dateadd(?1,?2,?3)";
+		return unit == SECOND
+				//TODO: if we have an integral number of seconds
+				//      (the common case) this is unnecessary
+				? "dateadd(nanosecond,?2*1e9,?3)"
+				: "dateadd(?1,?2,?3)";
 	}
 
 	@Override

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

@@ -300,6 +300,11 @@ public class HSQLDialect extends Dialect {
 			case WEEK:
 				pattern.append("dateadd('day',?2*7,");
 				break;
+			case SECOND:
+				//TODO: if we have an integral number of seconds
+				//      (the common case) this is unnecessary
+				pattern.append("timestampadd(sql_tsi_frac_second, ?2*1e9,");
+				break;
 			default:
 				pattern.append("dateadd('?1',?2,");
 		}

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

@@ -1303,7 +1303,7 @@ public class FunctionTests {
 	// really this could and should be made work on these dialects
 	@SkipForDialect(dialectClass = DerbyDialect.class)
 	@SkipForDialect(dialectClass = SQLServerDialect.class)
-	@SkipForDialect(dialectClass = SybaseDialect.class)
+	@SkipForDialect(dialectClass = SybaseDialect.class, matchSubTypes = true)
 	public void testAddSecondsWithFractionalPart(SessionFactoryScope scope) {
 		scope.inTransaction(
 				session -> {
@@ -1315,7 +1315,7 @@ public class FunctionTests {
 	}
 
 	@Test
-	@SkipForDialect(dialectClass = SybaseDialect.class)
+	@SkipForDialect(dialectClass = SybaseDialect.class, matchSubTypes = true)
 	public void testAddNanoseconds(SessionFactoryScope scope) {
 		scope.inTransaction(
 				session -> {