class SelectOrderBy {

    /**
     * The order by expression.
     */
    public Expression expression;

    /**
     * The column index expression. This can be a column index number (1 meaning
     * the first column of the select list) or a parameter (the parameter is a
     * number representing the column index number).
     */
    public Expression columnIndexExpr;

    /**
     * If the column should be sorted descending.
     */
    public boolean descending;

    /**
     * If NULL should be appear first.
     */
    public boolean nullsFirst;

    /**
     * If NULL should be appear at the end.
     */
    public boolean nullsLast;

    public String getSQL() {<FILL_FUNCTION_BODY>}
}

        StringBuilder buff = new StringBuilder();
        if (expression != null) {
            buff.append(expression.getSQL());
        } else {
            buff.append(columnIndexExpr.getSQL());
        }
        if (descending) {
            buff.append(" DESC");
        }
        if (nullsFirst) {
            buff.append(" NULLS FIRST");
        } else if (nullsLast) {
            buff.append(" NULLS LAST");
        }
        return buff.toString();
    
<no_super_class>