daviddoji-cs50/problems/2024/sql/moneyball@20260430T071337.725093184Z

1.sql

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+-- write a SQL query to find the average player salary by year.
+--     Sort by year in descending order.
+--     Round the salary to two decimal places and call the column “average salary”.
+--     Your query should return a table with two columns, one for year and one for average salary.
+SELECT "year", ROUND(AVG("salary"), 2) AS "average salary"
+FROM "salaries"
+GROUP BY "year"
+ORDER BY "year" DESC;

10.sql

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+-- To be precise, the table should include:
+--     All player’s first names
+--     All player’s last names
+--     All player’s salaries
+--     All player’s home runs
+--     The year in which the player was paid that salary and hit those home runs
+
+-- In 10.sql, write a query to return just such a table.
+--     Your query should return a table with five columns, per the above.
+--     Order the results, first and foremost, by player’s IDs (least to greatest).
+--     Order rows about the same player by year, in descending order.
+--     Consider a corner case: suppose a player has multiple salaries or performances for a given year.
+--     Order them first by number of home runs, in descending order, followed by salary, in descending order.
+--     Be careful to ensure that, for a single row, the salary’s year and the performance’s year match.
+SELECT p."first_name", p."last_name", s."salary", perf."HR", s."year"
+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"
+ORDER BY
+    p."id" ASC,
+    s."year" DESC,
+    perf."HR" DESC,
+    s."salary" DESC;

11.sql

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+-- 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 "dollars 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;

12.sql

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+-- write a SQL query to find the players among the 10 least expensive players per hit and among the 10 least expensive players per RBI in 2001.
+--     Your query should return a table with two columns, one for the players’ first names and one of their last names.
+--     You can calculate a player’s salary per RBI by dividing their 2001 salary by their number of RBIs in 2001.
+--     You may assume, for simplicity, that a player will only have one salary and one performance in 2001.
+--     Order your results by player ID, least to greatest (or alphabetically by last name, as both are the same in this case!).
+--     Keep in mind the lessons you’ve learned in 10.sql and 11.sql!
+WITH least_expensive_per_hit AS (
+    SELECT
+        p."id",
+        p."first_name",
+        p."last_name"
+    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
+        (s."salary" / perf."H") ASC,
+        p."first_name" ASC,
+        p."last_name" ASC
+    LIMIT 10
+),
+least_expensive_per_rbi AS (
+    SELECT
+        p."id",
+        p."first_name",
+        p."last_name"
+    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."RBI" > 0
+    ORDER BY
+        (s."salary" / perf."RBI") ASC,
+        p."first_name" ASC,
+        p."last_name" ASC
+    LIMIT 10
+)
+SELECT
+    h."first_name",
+    h."last_name"
+FROM least_expensive_per_hit AS h
+JOIN least_expensive_per_rbi AS r
+    ON h."id" = r."id"
+ORDER BY h."id" ASC;

2.sql

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+-- write a SQL query to find Cal Ripken Jr.’s salary history.
+--     Sort by year in descending order.
+--     Your query should return a table with two columns, one for year and one for salary.
+SELECT s."year", s."salary"
+FROM "salaries" AS s
+JOIN "players" AS p
+    ON s."player_id" = p."id"
+WHERE p."first_name" = "Cal" AND p."last_name" LIKE "Ripken%"
+ORDER BY "year" DESC;

3.sql

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+-- write a SQL query to find Ken Griffey Jr.’s home run history.
+--     Sort by year in descending order.
+--     Note that there may be two players with the name “Ken Griffey.” This Ken Griffey was born in 1969.
+--     Your query should return a table with two columns, one for year and one for home runs.
+SELECT perf."year", perf."hr"
+FROM "performances" AS perf
+JOIN "players" AS p
+    ON perf."player_id" = p."id"
+WHERE
+    p."first_name" = "Ken"
+    AND
+    p."last_name" LIKE "Griffey%"
+    AND
+    p."birth_year" = "1969"
+ORDER BY "year" DESC;

4.sql

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+-- write a SQL query to find the 50 players paid the least in 2001.
+--     Sort players by salary, lowest to highest.
+--     If two players have the same salary, sort alphabetically by first name and then by last name.
+--     If two players have the same first and last name, sort by player ID.
+--     Your query should return three columns, one for players’ first names, one for their last names, and one for their salaries.
+SELECT
+    p."first_name", p."last_name", s."salary"
+FROM "players" AS p
+JOIN "salaries" AS s
+    ON s."player_id" = p."id"
+WHERE s."year" = "2001"
+ORDER BY s."salary" ASC, p."first_name" ASC, p."last_name" ASC, p."id" ASC
+LIMIT 50;

5.sql

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+-- write a SQL query to find all teams that Satchel Paige played for.
+--     Your query should return a table with a single column, one for the name of the teams.
+SELECT DISTINCT t."name"
+FROM "teams" AS t
+JOIN "performances" AS perf
+    ON perf."team_id" = t."id"
+JOIN "players" AS p
+    ON p."id" = perf."player_id"
+WHERE p."first_name" = "Satchel" AND p."last_name" = "Paige";

6.sql

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+-- write a SQL query to return the top 5 teams, sorted by the total number of hits by players in 2001.
+--     Call the column representing total hits by players in 2001 “total hits”.
+--     Sort by total hits, highest to lowest.
+--     Your query should return two columns, one for the teams’ names and one for their total hits in 2001.
+SELECT
+    t."name",
+    SUM(perf."H") AS "total hits"
+FROM "teams" AS t
+JOIN "performances" AS perf
+    ON perf."team_id" = t."id"
+WHERE perf."year" = '2001'
+GROUP BY t."id", t."name"
+ORDER BY "total hits" DESC
+LIMIT 5;

7.sql

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+-- write a SQL query to find the name of the player who’s been paid the highest salary, of all time, in Major League Baseball.
+--     Your query should return a table with two columns, one for the player’s first name and one for their last name.
+SELECT p."first_name", p."last_name"
+FROM "players" AS p
+JOIN "salaries" AS s
+    ON s."player_id" = p."id"
+ORDER BY s."salary" DESC
+LIMIT 1;

8.sql

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+-- write a SQL query to find the 2001 salary of the player who hit the most home runs in 2001.
+--     Your query should return a table with one column, the salary of the player.
+SELECT s."salary"
+FROM "salaries" AS s
+JOIN "performances" AS perf
+    ON perf."player_id" = s."player_id"
+WHERE s."year" = '2001' AND perf."year" = '2001'
+ORDER BY perf."HR" DESC
+LIMIT 1;

9.sql

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+-- write a SQL query to find the 5 lowest paying teams (by average salary) in 2001.
+--     Round the average salary column to two decimal places and call it “average salary”.
+--     Sort the teams by average salary, least to greatest.
+--     Your query should return a table with two columns, one for the teams’ names and one for their average salary.
+SELECT
+    t."name",
+    ROUND(AVG(s."salary"), 2) AS "average salary"
+FROM "teams" AS t
+JOIN "salaries" AS s
+    ON s."team_id" = t."id"
+WHERE s."year" = '2001'
+GROUP BY t."id", t."name"
+ORDER BY "average salary" ASC
+LIMIT 5;