Ambiguous column names in derived table

[Richard Cyganiak]

Hi,

Suppose I have two tables Tbl1 and Tbl2. Both have a column called A.

MySQL 5.0.7 rejects this query as ambiguous:

SELECT A from Tbl1, Tbl2;

But it accepts this and returns the A column from Tbl1:

SELECT A FROM (SELECT * FROM Tbl1, Tbl2) AS foo;

But this query is rejected again:

SELECT * FROM (SELECT * FROM Tbl1, Tbl2) AS foo ORDER BY A;

Why is this? Is it a bug?

Thanks,
Richard