Postgres stored function return result of SELECT DISTINCT - sql

Question

I want to have an array of distinct integer values across my postgres table as the return value of a stored function.
The stored function currently looks like this
create or replace function get_unique_entries(id int)
returns table ("entry_id" int)
language plpgsql
as
$$
begin
return query
select distinct table.entry_id
from my_table
where x = id;
end;
$$;
When executing
select get_unique_entries(2);, I get the following error message:
structure of query does not match function result type
I tried different return types, but nothing worked for me.
Thanks in advance!

Answer 1

Hmm, can you give us a more complete picture of your scenario? I tried using your code and it seems to work (except I needed to replace table with my_table):
postgres=# create table my_table(x int, entry_id int, name text);
CREATE TABLE
postgres=# insert into my_table values(generate_series(1,100),generate_series(1,10),'foo');
INSERT 0 100
postgres=# create or replace function get_unique_entries(id int)
postgres-# returns table ("entry_id" int)
postgres-# language plpgsql
postgres-# as
postgres-# $$
postgres$# begin
postgres$# return query
postgres$# select distinct table.entry_id
postgres$# from my_table
postgres$# where x = id;
postgres$# end;
postgres$# $$;
ERROR: syntax error at or near "table"
LINE 8: select distinct table.entry_id
^
postgres=# create or replace function get_unique_entries(id int)
returns table ("entry_id" int)
language plpgsql
as
$$
begin
return query
select distinct my_table.entry_id
from my_table
where x = id;
end;
$$;
CREATE FUNCTION
postgres=# select get_unique_entries(2);
get_unique_entries
--------------------
2
(1 row)
postgres=#

Answer 2

While preparing the complete example I actually found it out myself.
As I am working with supabase, they display the datatype BIGINT as int8. I was trying to set this as return type. Setting the return type to BIGINT instead worked.
So in general check I would recommend myself and to others to check your column data types exactly.
The working example looks like this (as indicated by #richyen)
create or replace function get_unique_categories_for_platform(platformId int)
returns table ("category_fk" bigint)
language plpgsql
as
$$
begin
return query select distinct course.category_fk
from course
where platform_fk = platformId;
end;
$$;