Using an array variable in WHERE NOT IN -like clause - postgresql

Question

I have declared an array variable as
select array(select "account_id" from [some where clause]) as negateArray;
Note that I return a single column. Now I need to use it in another WHERE-clause that should mean: do NOT include data if account_id matches any of found in negateArray.
I write something like
select * from [some other where clause] WHERE (account_id NOT IN ANY(negateArray));
but I am getting a syntax error. What would be the correct way to write the condition for PostgreSQL?

Answer 1

In order to let the optimizer do its best - convert the not in condition to left [outer] join. Here is an equivalent SQL-only version rewrite:
select t2.*
from outer_table t2
left join (select account_id from inner_table where [some where clause on inner_table]) t1
on t2.account_id = t1.account_id
where [some other where clause on outer_table]
AND t1.account_id IS NULL;
t1.account_id IS NULL does the not in job.
Edit
Equivalent but shorter (and probably more efficient) using [inner] join and inverted condition:
select t2.*
from outer_table t2
join (select account_id from inner_table where NOT [some where clause on inner_table]) t1
on t2.account_id = t1.account_id
where [some other where clause on outer_table];

Answer 2

If you want to use variables, then you need to do this using procedure/function.
First, define variable as negateArray int[]
Then try:
select array(select "account_id" from [some where clause]) INTO negateArray;
and then:
select * from [some other where clause] WHERE (account_id <> ANY(negateArray));
EDIT
For "pure" SQL, you don't need variable, just use query like this:
select * from [some other where clause] -- your second query
WHERE account_id NOT IN(
select "account_id" from [some where clause] -- your first query
);