-- write a SQL query to find the 10 least expensive players per hit in 2001.
--     Your query should return a table with three columns, one for the players’ first names, one of their last names,
-- and one called “dollars per hit”.
--     You can calculate the “dollars per hit” column by dividing a player’s 2001 salary by the number of hits they made
-- in 2001. Recall you can use AS to rename a column.
--     Dividing a salary by 0 hits will result in a NULL value. Avoid the issue by filtering out players with 0 hits.
--     Sort the table by the “dollars per hit” column, least to most expensive. If two players have the same “dollars per
-- hit”, order by first name, followed by last name, in alphabetical order.
--     As in 10.sql, ensure that the salary’s year and the performance’s year match.
--     You may assume, for simplicity, that a player will only have one salary and one performance in 2001.
SELECT
    p."first_name",
    p."last_name",
    (s."salary" / perf."H") AS "dollar per hit"
FROM "players" AS p
JOIN "salaries" AS s
    ON s."player_id" = p."id"
JOIN "performances" as perf
    ON perf."player_id" = p."id"
    AND perf."year" = s."year"
WHERE
    s."year" = '2001'
    AND perf."H" > 0
ORDER BY
    "dollars per hit" ASC,
    p."first_name" ASC,
    p."last_name" ASC
LIMIT 10;