Use default values for the values section of an insert statement for hsqldb as well as postgres

It blows up expecting a column name in the values parenthesis, but the default values string that
postgres was working seems to work. It's not in http://hsqldb.org/doc/guide/ch09.html, but so it
goes.

src/main/java/com/samskivert/depot/impl/BuildVisitor.java

@@ -919,6 +919,12 @@ public abstract class BuildVisitor implements FragmentVisitor<Void>
         }
     }
 
+    // output the column name and value portion of an insert when all values are defaulted
+    protected void appendEmptyInsertValues ()
+    {
+        _builder.append("default values");
+    }
+
     // output the column names and values for an insert
     protected void appendInsertColumns (InsertClause insertClause)
     {
@@ -928,6 +934,18 @@ public abstract class BuildVisitor implements FragmentVisitor<Void>
         Set<String> idFields = insertClause.getIdentityFields();
         ColumnExp<?>[] fields = marsh.getColumnFieldNames();
 
+        boolean insertingSomething = false;
+        for (ColumnExp<?> field : fields) {
+            if (!idFields.contains(field.name)) {
+                insertingSomething = true;
+                break;
+            }
+        }
+        if (!insertingSomething) {
+            appendEmptyInsertValues();
+            return;
+        }
+
         _builder.append("(");
         boolean comma = false;
         for (ColumnExp<?> field : fields) {

src/main/java/com/samskivert/depot/impl/MySQLBuilder.java

@@ -155,6 +155,11 @@ public class MySQLBuilder
             bindValue(fullText.getQuery());
             _builder.append(" in boolean mode)");
         }
+
+        @Override protected void appendEmptyInsertValues ()
+        {
+            _builder.append("() values ()");
+        }
     }
 
     public MySQLBuilder (DepotTypes types)

src/main/java/com/samskivert/depot/impl/PostgreSQLBuilder.java

@@ -22,8 +22,6 @@ import com.samskivert.depot.Exps;
 import com.samskivert.depot.PersistentRecord;
 import com.samskivert.depot.annotation.FullTextIndex.Configuration;
 import com.samskivert.depot.annotation.FullTextIndex;
-import com.samskivert.depot.clause.InsertClause;
-import com.samskivert.depot.expression.ColumnExp;
 import com.samskivert.depot.impl.expression.IntervalExp;
 import com.samskivert.depot.impl.expression.DateFun.DatePart;
 import com.samskivert.depot.impl.expression.DateFun.DateTruncate;
@@ -121,22 +119,6 @@ public class PostgreSQLBuilder
             _builder.append("\"").append(field).append("\"");
         }
 
-        @Override protected void appendInsertColumns (InsertClause insertClause)
-        {
-            // see if we will be inserting any columns whatsoever
-            Class<? extends PersistentRecord> pClass = insertClause.getPersistentClass();
-            Set<String> idFields = insertClause.getIdentityFields();
-            for (ColumnExp<?> field : _types.getMarshaller(pClass).getColumnFieldNames()) {
-                if (!idFields.contains(field.name)) {
-                    // we found a field we're inserting, so call super and finish
-                    super.appendInsertColumns(insertClause);
-                    return;
-                }
-            }
-            // we never found anything we'll actually be inserting
-            _builder.append("default values");
-        }
-
         protected PGBuildVisitor (DepotTypes types)
         {
             super(types, true);