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Medium/Activity Participants.sql

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+-- Question 77
+-- Table: Friends
+
+-- +---------------+---------+
+-- | Column Name   | Type    |
+-- +---------------+---------+
+-- | id            | int     |
+-- | name          | varchar |
+-- | activity      | varchar |
+-- +---------------+---------+
+-- id is the id of the friend and primary key for this table.
+-- name is the name of the friend.
+-- activity is the name of the activity which the friend takes part in.
+-- Table: Activities
+
+-- +---------------+---------+
+-- | Column Name   | Type    |
+-- +---------------+---------+
+-- | id            | int     |
+-- | name          | varchar |
+-- +---------------+---------+
+-- id is the primary key for this table.
+-- name is the name of the activity.
+ 
+
+-- Write an SQL query to find the names of all the activities with neither maximum, nor minimum number of participants.
+
+-- Return the result table in any order. Each activity in table Activities is performed by any person in the table Friends.
+
+-- The query result format is in the following example:
+
+-- Friends table:
+-- +------+--------------+---------------+
+-- | id   | name         | activity      |
+-- +------+--------------+---------------+
+-- | 1    | Jonathan D.  | Eating        |
+-- | 2    | Jade W.      | Singing       |
+-- | 3    | Victor J.    | Singing       |
+-- | 4    | Elvis Q.     | Eating        |
+-- | 5    | Daniel A.    | Eating        |
+-- | 6    | Bob B.       | Horse Riding  |
+-- +------+--------------+---------------+
+
+-- Activities table:
+-- +------+--------------+
+-- | id   | name         |
+-- +------+--------------+
+-- | 1    | Eating       |
+-- | 2    | Singing      |
+-- | 3    | Horse Riding |
+-- +------+--------------+
+
+-- Result table:
+-- +--------------+
+-- | activity     |
+-- +--------------+
+-- | Singing      |
+-- +--------------+
+
+-- Eating activity is performed by 3 friends, maximum number of participants, (Jonathan D. , Elvis Q. and Daniel A.)
+-- Horse Riding activity is performed by 1 friend, minimum number of participants, (Bob B.)
+-- Singing is performed by 2 friends (Victor J. and Jade W.)
+
+-- Solution
+with t1 as(
+select max(a.total) as total
+from(
+    select activity, count(*) as total
+    from friends
+    group by activity) a
+	union all
+	select min(b.total) as low
+    from(
+    select activity, count(*) as total
+    from friends
+    group by activity) b), 
+t2 as
+(
+    select activity, count(*) as total
+    from friends
+    group by activity
+)
+
+select activity
+from t1 right join t2
+on t1.total = t2.total
+where t1.total is null
+	

Medium/Running total for different genders.sql

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+-- Question 76
+-- Table: Scores
+
+-- +---------------+---------+
+-- | Column Name   | Type    |
+-- +---------------+---------+
+-- | player_name   | varchar |
+-- | gender        | varchar |
+-- | day           | date    |
+-- | score_points  | int     |
+-- +---------------+---------+
+-- (gender, day) is the primary key for this table.
+-- A competition is held between females team and males team.
+-- Each row of this table indicates that a player_name and with gender has scored score_point in someday.
+-- Gender is 'F' if the player is in females team and 'M' if the player is in males team.
+ 
+
+-- Write an SQL query to find the total score for each gender at each day.
+
+-- Order the result table by gender and day
+
+-- The query result format is in the following example:
+
+-- Scores table:
+-- +-------------+--------+------------+--------------+
+-- | player_name | gender | day        | score_points |
+-- +-------------+--------+------------+--------------+
+-- | Aron        | F      | 2020-01-01 | 17           |
+-- | Alice       | F      | 2020-01-07 | 23           |
+-- | Bajrang     | M      | 2020-01-07 | 7            |
+-- | Khali       | M      | 2019-12-25 | 11           |
+-- | Slaman      | M      | 2019-12-30 | 13           |
+-- | Joe         | M      | 2019-12-31 | 3            |
+-- | Jose        | M      | 2019-12-18 | 2            |
+-- | Priya       | F      | 2019-12-31 | 23           |
+-- | Priyanka    | F      | 2019-12-30 | 17           |
+-- +-------------+--------+------------+--------------+
+-- Result table:
+-- +--------+------------+-------+
+-- | gender | day        | total |
+-- +--------+------------+-------+
+-- | F      | 2019-12-30 | 17    |
+-- | F      | 2019-12-31 | 40    |
+-- | F      | 2020-01-01 | 57    |
+-- | F      | 2020-01-07 | 80    |
+-- | M      | 2019-12-18 | 2     |
+-- | M      | 2019-12-25 | 13    |
+-- | M      | 2019-12-30 | 26    |
+-- | M      | 2019-12-31 | 29    |
+-- | M      | 2020-01-07 | 36    |
+-- +--------+------------+-------+
+-- For females team:
+-- First day is 2019-12-30, Priyanka scored 17 points and the total score for the team is 17.
+-- Second day is 2019-12-31, Priya scored 23 points and the total score for the team is 40.
+-- Third day is 2020-01-01, Aron scored 17 points and the total score for the team is 57.
+-- Fourth day is 2020-01-07, Alice scored 23 points and the total score for the team is 80.
+-- For males team:
+-- First day is 2019-12-18, Jose scored 2 points and the total score for the team is 2.
+-- Second day is 2019-12-25, Khali scored 11 points and the total score for the team is 13.
+-- Third day is 2019-12-30, Slaman scored 13 points and the total score for the team is 26.
+-- Fourth day is 2019-12-31, Joe scored 3 points and the total score for the team is 29.
+-- Fifth day is 2020-01-07, Bajrang scored 7 points and the total score for the team is 36.
+
+-- Solution
+select gender, day, 
+sum(score_points) over(partition by gender order by day) as total
+from scores
+group by 1,2
+order by 1,2