Tagged Questions
1
vote
2answers
92 views
Getting SELECT to return a constant value even if zero rows match
Consider this select statement:
SELECT *,
1 AS query_id
FROM players
WHERE username='foobar';
It returns the column query_id with value 1 along with a player's other columns.
How would ...
9
votes
1answer
387 views
Why does NOT IN with a set containing NULL always return FALSE/NULL?
I had a query (for Postgres and Informix) with a NOT IN clause containing a subquery that in some cases returned NULL values, causing that clause (and the entire query) to fail to return anything.
...
9
votes
3answers
4k views
PostgreSQL multi-column unique constraint and NULL values
I have a table like the following:
create table my_table (
id int8 not null,
id_A int8 not null,
id_B int8 not null,
id_C int8 null,
constraint pk_my_table primary key (id),
constraint ...
3
votes
1answer
363 views
PostgreSQL pl/perl trigger, differentiate null vs empty
I've been trying to speed up a generic auditing trigger that I had written in pl/pgsql some time back. On update, it generates a list of columns in the table being updated and inserts rows in the ...
3
votes
2answers
835 views
PostgreSQL: count datasets / lines containing NULL values
I'm looking for a easy function to get the number of datasets (of any table) containing NULL values. It's not important how many columns are involved.
For example:
CREATE TABLE tab1 (
id INTEGER ...
5
votes
4answers
2k views
Finding empty columns of a table in PostgreSQL
What query would return the name of the columns of a table where all rows are NULL?
