BUG #16834: where-in: if the nested query fails, the parent query returns all the records
The following bug has been logged on the website:
Bug reference: 16834
Logged by: Flavio Ricci
Email address: flavio.ricci82@gmail.com
PostgreSQL version: 11.9
Operating system: x86_64-pc-linux-gnu
Description:
Hi,
I have found out that in a where-in query if the nested query fails, the
parent query returns all the records if the where condition field matches
with the selected field in the inner query.
Example:
SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')
If you run only the nested query it fails because the field does not exist
for table_b
If you run all the query, it returns all the records of table_a
Regards,
Flavio
On Fri, Jan 22, 2021 at 12:57 PM PG Bug reporting form <
noreply@postgresql.org> wrote:
The following bug has been logged on the website:
Bug reference: 16834
Logged by: Flavio Ricci
Email address: flavio.ricci82@gmail.com
PostgreSQL version: 11.9
Operating system: x86_64-pc-linux-gnu
Description:Hi,
I have found out that in a where-in query if the nested query fails, the
parent query returns all the records if the where condition field matches
with the selected field in the inner query.
Example:
SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')If you run only the nested query it fails because the field does not exist
for table_b
If you run all the query, it returns all the records of table_aRegards,
Flavio
This is not a bug. Returning all records of the parent table is the correct
result, due to scope resolution.
The column field_only_in_parent_table does not have a table prefix so it is
first checked whether it's a column of the immediate tables (table_b here).
Since the column is not there, the next level tables are checked (table_a
here). It is a there so the query is executed as:
SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT table_a.field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')
On Fri, Jan 22, 2021 at 2:38 PM Pantelis Theodosiou <ypercube@gmail.com>
wrote:
On Fri, Jan 22, 2021 at 12:57 PM PG Bug reporting form <
noreply@postgresql.org> wrote:The following bug has been logged on the website:
Bug reference: 16834
Logged by: Flavio Ricci
Email address: flavio.ricci82@gmail.com
PostgreSQL version: 11.9
Operating system: x86_64-pc-linux-gnu
Description:Hi,
I have found out that in a where-in query if the nested query fails, the
parent query returns all the records if the where condition field matches
with the selected field in the inner query.
Example:
SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')If you run only the nested query it fails because the field does not exist
for table_b
If you run all the query, it returns all the records of table_aRegards,
Flavio
This is not a bug. Returning all records of the parent table is the
correct result, due to scope resolution.The column field_only_in_parent_table does not have a table prefix so it
is first checked whether it's a column of the immediate tables (table_b
here). Since the column is not there, the next level tables are checked
(table_a here). It is a there so the query is executed as:SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT table_a.field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')
To be accurate the rows of table a that are returned are the ones wit
non-null values in field_only_in_parent_table and only if table b has at
least one row.
If table b has 0 rows, then the query returns no rows.
Hi Theodosiou,,
thank you very much for your answer
It seems that I ran into a tricky situation, but your explanation helped me
definitely about what is happening behind the curtains
Thanks again
Best regards,
Flavio
Il giorno ven 22 gen 2021 alle ore 15:49 Pantelis Theodosiou <
ypercube@gmail.com> ha scritto:
Show quoted text
On Fri, Jan 22, 2021 at 2:38 PM Pantelis Theodosiou <ypercube@gmail.com>
wrote:On Fri, Jan 22, 2021 at 12:57 PM PG Bug reporting form <
noreply@postgresql.org> wrote:The following bug has been logged on the website:
Bug reference: 16834
Logged by: Flavio Ricci
Email address: flavio.ricci82@gmail.com
PostgreSQL version: 11.9
Operating system: x86_64-pc-linux-gnu
Description:Hi,
I have found out that in a where-in query if the nested query fails, the
parent query returns all the records if the where condition field matches
with the selected field in the inner query.
Example:
SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')If you run only the nested query it fails because the field does not
exist
for table_b
If you run all the query, it returns all the records of table_aRegards,
Flavio
This is not a bug. Returning all records of the parent table is the
correct result, due to scope resolution.The column field_only_in_parent_table does not have a table prefix so it
is first checked whether it's a column of the immediate tables (table_b
here). Since the column is not there, the next level tables are checked
(table_a here). It is a there so the query is executed as:SELECT *
FROM table_a
WHERE field_only_in_parent_table IN (
SELECT table_a.field_only_in_parent_table
FROM table_b
WHERE name = 'John Doe')To be accurate the rows of table a that are returned are the ones wit
non-null values in field_only_in_parent_table and only if table b has at
least one row.
If table b has 0 rows, then the query returns no rows.
On Friday, January 22, 2021, PG Bug reporting form <noreply@postgresql.org>
wrote:
If you run only the nested query it fails because the field does not exist
for table_b
If you run all the query, it returns all the records of table_a
David J.