Re: BUG #12276: Using old name of a renamed or dropped column in a sub-query does not throw error

collin.peters@gmail.com wrote:

> Basically if you rename a column, and then use the original name in a
> subquery, that sub-query does not complain that the column no longer exists,
> and seems to complete ok. This will cause whatever SELECT or DELETE that is
> using the sub-query to continue on its merry way and cause havoc.

It's not using the old name of the column --- it's using the name of the
OTHER column, that is, the column of the same name in the other table.
In essence, your subquery always returns true.

> -- select on value of 'bar' and orders for user 1
> -- FAIL - returns all three order lines of 'bar'
> SELECT     *
> FROM    order_lines
> WHERE   value = 'bar'
> AND     order_id IN (
>     -- THIS SHOULD FAIL!! THIS COLUMN NAME DOES NOT EXIST ANYMORE
>     SELECT  order_id
>     FROM    users
>     WHERE   user_id = 1
> );
>
> -- same delete as above, except value of 'bar'
> DELETE
> FROM    order_lines
> WHERE   value = 'bar'
> AND     order_id IN (
>     -- THIS SHOULD FAIL!! THIS COLUMN NAME DOES NOT EXIST ANYMORE
>     SELECT  order_id
>     FROM    users
>     WHERE   user_id = 1
> );


--
Álvaro Herrera                http://www.2ndQuadrant.com/
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