Re: BUG #14919: Invalid column in sub select is still a valid select

On Mon, Nov 20, 2017 at 3:49 PM, Tanes Sriviroolchai <tanes(at)siamscan(dot)net>
wrote:

> Really? The fact that 1st statement doen't end in exception throwing is
> ok? (While the same sub select executes with exception throwing.)
>
> select * from a where id=(select id from b where descr='A');
>

Because "b" doesn't have a column called "id", this is the same as:

select * from a where id=(select a.id from b where descr='A');

and that's a valid, though slightly silly, query. In other words, you
accidentally wrote a correlated subquery. Some people consider it good
practice to qualify column references with the name of the table when
there's more than one column in scope. If you had written:

select * from a where id=(select b.id from b where b.descr='A');

you would have noticed that you made a mistake, due to the exception this
query raises.

.m