Where or Having clause and COUNT(1)

Question

I'm having trouble trying to figure out the way to get the conditional difference between two counts in a where clause.
I would like to scan a table and only select records where the record count of one column attribute is different than another.
I have
select name, count(1) from skill <<< TOTAL_COUNT
and
select name, count(1) from skill where score is not NULL <<<< SCORED_COUNT
I want to have a statement that just returns the names for those where TOTAL_COUNT - SCORED_COUNT = 0
... meaning those names where any of the rows have not been scored.
I've tried a "having clause" but it still returns all there names. Even those there TOTAL_COUNT - SCORED_COUNT > 0
Here's the non-working code....
select * from
(select full_name
from emp e
where e.manager = 'Smith, John'
having
((select count(1)
from emp_skill es
where es.emp_fk = e.id
group by null) -
(select count(1)
from emp_skill es1
where es1.emp_fk = e.id and
es1.self_prof is not NULL
group by null)) = 0
)

Answer 1

Don't take 3360 too seriously in this context. COUNT(expression) is a bit of a running joke around these parts.
However, his response does contain the seed of the solution for your problem.
COUNT(<expression>) works because the COUNT function counts all rows with a non-null value for expression. So COUNT('Chocula') counts the non-null occurences of the literal string 'Chocula' in the table. Obviously, this counts every row in the table. COUNT(*) counts all the non-null occurences of a row in the table (even a row with all null values is a row). Clearly these are equivalent.
However, if <expression> evaluates differently for each row, then COUNT(*) and COUNT(<expression>) can differ. So, for your example, assuming that the scored column is truly NULL in some records, what you need is something like:
SQL> SELECT * FROM skill;
NAME            SCORE
BOB                 5
BOB                 6
BOB                 7
BILL                5
BILL                8
BILL
SQL> SELECT name, total, scored
  2  FROM (SELECT name, count(*) total, count(score) scored
  3        FROM skill
  4        GROUP BY name)
  5  WHERE total <> scored;
NAME            TOTAL     SCORED
BILL                3          2