Question

I’ve got an association table that groups accounts together.

I’m trying to select a subset of table ‘target’

p_group_id := 7;

select *
target t
where  t.account_id in get_account_ids(p_group_id);

Is it possible to write a function that returns a list of account_ids (as some form of collection) that would facilitate the above code?

I’ve looked at pipelined functions, however I want to stay away from loops and cursors. Also, custom types / table also get into casting that I’d like to avoid.

For reference, here’s some pseudocode for what the function ‘get_account_ids’ would do, hypothetically:

function get_account_ids(p_group_id) 
  insert into v_ret
  select aa.account_id
  from   assoc_account aa
  where  aa.groupid = p_group_id;

return v_ret;

Answer 1

You simply need:

select *
from   target t
where  t.account_id in 
       ( select aa.account_id
         from   assoc_account aa
         where  aa.groupid = 7;
       )

The above will work, assuming that assoc_account.account_id is never NULL.