Value alias in sql statement doesn't work in render_sql

[jyginger]

Hi,
the sql statement like below:

$sql = " SELECT '0' `fid`,`name`,`id` FROM `testtable`";
$tree->render_sql($sql,"id","name","","fid"); // not work
$tree->render_table("temp","id","name","","fid");  // work, and "temp" is the temp table created by above $sql

How could I use render_sql? thanks in advance.