Oliver Dizon schrieb am 27.01.2015 um 11:46:
> I hope I'm in the right place to throw this. I just want to ask the reason behind this weird scenario.
>
> All records were deleted in a table even if the subquery in the where clause has a missing a column.
>
> --from a certain script where table_id is not yet existing on table_sample
>
> delete from main_table_sample where table_id in (select table_id from table_sample);
>
> Im expecting that postgres will return an ERROR message like
> 'column "table_id" does not exist on table table_sample'
>
> But it did not returned any error and deleted all the records instead.
>
> Version: psql (8.4.9, server 9.2.5)
>No, this is correct and complies with the SQL standard. If you reference a column in a sub-select that is available
inthe outer query but not in the sub-select, then it's automatically a reference to the column from the outer query.
>So in your query, the column "table_id" in the sub-query references the main_table_sample.table_id.
>I agree this is confusing, but it's the way it was specified in the SQL standard.
>Thomas
Yea. I've realized that it's yet another example of "outer
reference". I guess I really need to read another SQL book again :-)
Thanks!
______________________
Oliver G. Dizon
Z Getcare Systems Team
RTZ Associates, Inc.
johnoliver@rtzassociates.com