throw new UnsupportedSQLException("Aggregate used as regular function",
node.getSQLsource());
else if (node instanceof ColumnDefaultExpression)
return assembleColumnDefault(((ColumnDefaultExpression)node).getColumn(), null);
else if (node instanceof IsNullIndexKey)
return new TNullExpression(node.getType());
else
throw new UnsupportedSQLException("Unknown expression", node.getSQLsource());
}