Another MAX() function question...

Question

Help was provided earlier for a question I had regarding use of the MAX function... This also pertains to that. I have two tables, employee and movie. I want to find the name of the employee who has entered the most amount of movies into our database. The query I have come up with so far (it's a little messy) is:
SQL> select firstname, max(m) from (select firstname, count(enteredby) m from em
ployee, movie where enteredby = id group by firstname) group by firstname;
FIRSTNAME MAX(M)
Peter 6
Swanson 5
Kevin 7
Beverly 3
So I have this table returned, now in this case I want to be able to select from this subquery the first name "Kevin", since he has entered in the most movies. In my head this seems so easy, "Grab the firstname of the person whose max(m) is the largest", but I am just having trouble getting this thought translated into a proper query!

Answer 1

You can always do
SELECT firstname
  FROM (SELECT firstname, RANK() OVER (ORDER BY max_m) rnk
          FROM (<<your query>>))
WHERE rnk = 1Note that you'll need to alias the MAX(m) result first. You could also do
SELECT firstname
  FROM (
SELECT firstname, RANK() OVER( ORDER BY cnt) rnk
  FROM (SELECT firstname, COUNT(enteredby) cnt
          FROM employee e, movie m
        WHERE enteredby = id
        GROUP BY firstname)
WHERE rnk = 1From a style standpoint, I would suggest that you get in the habit of aliasing your tables in your FROM clause and putting that alias on every column name to make it clear which table a particular column was selected from.
I would also suggest that you come up with a column naming convention that caused the same value to be named the same (or similar) thing in different tables. Joining an ID column from one table to an ENTEREDBY, for example, would be a non-obvious bit of logic. It probably makes more sense to have an EMPLOYEE_ID and an ENTERED_EMPLOYEE_ID column.
Justin