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‎Medium/Active Businesses.sql‎

Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -51,3 +51,43 @@ on e.event_type = b.event) c
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where c.occurences>c.average
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group by c.business_id
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having count(*) > 1
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-- My Solution:
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**Schema (MySQL v8.0)**
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CREATE TABLE Events (
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`business_id` INTEGER,
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`event_type` VARCHAR(10),
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`occurences` INTEGER
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);
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INSERT INTO Events
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(`business_id`, `event_type`, `occurences`)
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VALUES
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('1', 'reviews', '7'),
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('3', 'reviews', '3'),
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('1', 'ads', '11'),
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('2', 'ads', '7'),
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('3', 'ads', '6'),
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('1', 'page views', '3'),
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('2', 'page views', '12');
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---
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**Query #1**
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select business_id from (
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select business_id, event_type, (case when occurences > (select avg(s.occurences) as avg_occurence from Events s
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where event_type = e.event_type) then 1 else 0 end ) as num_occurence
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from Events e ) s1
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group by business_id
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having sum(num_occurence) > 1 ;
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| business_id |
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| ----------- |
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| 1 |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/szNMC8LUuNaZhta4mKSaqQ/1)

‎Medium/Active Users.sql‎

Lines changed: 53 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -74,4 +74,56 @@ select distinct a.id, a.name from t1
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inner join accounts a
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on t1.id = a.id
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where datediff(t1.date_5,login_date) = 4
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order by id
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order by id
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-- My Solution:
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**Schema (MySQL v8.0)**
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CREATE TABLE Accounts (
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`id` INTEGER,
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`name` VARCHAR(8)
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);
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INSERT INTO Accounts
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(`id`, `name`)
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VALUES
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('1', 'Winston'),
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('7', 'Jonathan');
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CREATE TABLE Logins (
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`id` INTEGER,
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`login_date` DATETIME
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);
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INSERT INTO Logins
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(`id`, `login_date`)
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VALUES
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('7', '2020-05-30'),
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('1', '2020-05-30'),
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('7', '2020-05-31'),
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('7', '2020-06-01'),
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('7', '2020-06-02'),
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('7', '2020-06-02'),
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('7', '2020-06-03'),
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('1', '2020-06-07'),
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('7', '2020-06-10');
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---
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**Query #1**
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With cte as
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(select id, login_date, lead(login_date, 4) over(partition by id order by login_date) as lead_date
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from ( select distinct * from Logins ) d)
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select cte.id, a.name
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from cte left join Accounts a on cte.id = a.id
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where datediff(cte.lead_date, cte.login_date) = 4;
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| id | name |
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| --- | -------- |
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| 7 | Jonathan |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/6ibFyqXzwhQdpgiZc7Dtmh/1)

‎Medium/Activity Participants.sql‎

Lines changed: 54 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -85,4 +85,57 @@ select activity
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from t1 right join t2
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on t1.total = t2.total
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where t1.total is null
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-- My Solution:
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**Schema (MySQL v8.0)**
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CREATE TABLE Friends (
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`id` INTEGER,
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`name` VARCHAR(11),
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`activity` VARCHAR(12)
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);
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INSERT INTO Friends
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(`id`, `name`, `activity`)
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VALUES
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('1', 'Jonathan D.', 'Eating'),
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('2', 'Jade W.', 'Singing'),
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('3', 'Victor J.', 'Singing'),
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('4', 'Elvis Q.', 'Eating'),
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('5', 'Daniel A.', 'Eating'),
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('6', 'Bob B.', 'Horse Riding');
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CREATE TABLE Activities (
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`id` INTEGER,
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`name` VARCHAR(12)
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);
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INSERT INTO Activities
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(`id`, `name`)
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VALUES
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('1', 'Eating'),
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('2', 'Singing'),
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('3', 'Horse Riding');
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---
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**Query #1**
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with cte as ( select f.activity, cnt
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from Friends f left join
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(select activity, count(1) as cnt from Friends
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group by activity) s
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on f.activity = s.activity )
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select distinct activity from cte
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where cnt != (select min(cnt) from cte)
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and cnt != (select max(cnt) from cte);
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| activity |
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| -------- |
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| Singing |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/6aH4JYJuAYagoD9VghhH84/1)

‎Medium/All people report to the given manager.sql‎

Lines changed: 48 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -69,4 +69,51 @@ where manager_id = any (select employee_id
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from employees
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where manager_id = any (select employee_id
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from employees
72-
where manager_id = 1 and employee_id != 1))
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where manager_id = 1 and employee_id != 1))
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-- My Solution:
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**Schema (MySQL v8.0)**
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CREATE TABLE Employees (
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`employee_id` INTEGER,
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`employee_name` VARCHAR(6),
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`manager_id` INTEGER
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);
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INSERT INTO Employees
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(`employee_id`, `employee_name`, `manager_id`)
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VALUES
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('1', 'Boss', '1'),
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('3', 'Alice', '3'),
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('2', 'Bob', '1'),
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('4', 'Daniel', '2'),
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('7', 'Luis', '4'),
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('8', 'Jhon', '3'),
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('9', 'Angela', '8'),
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('77', 'Robert', '1');
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---
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**Query #1**
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with cte as
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(
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select employee_id from Employees where manager_id in (
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select employee_id from Employees where manager_id in (
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select employee_id from Employees where manager_id = 1 )
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)
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)
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select distinct * from cte
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where employee_id != 1;
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| employee_id |
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| ----------- |
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| 2 |
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| 4 |
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| 7 |
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| 77 |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/fFWPuXXsQE4AnByAjuJXGb/1)

‎Medium/Apples & Oranges.sql‎

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Original file line numberDiff line numberDiff line change
@@ -59,4 +59,48 @@ join
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(select sale_date as sale, fruit, sold_num as sold
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from sales
6161
where fruit = 'oranges') b
62-
on a.sale_date = b.sale)
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on a.sale_date = b.sale)
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-- My Solution:
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**Schema (MySQL v8.0)**
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CREATE TABLE Sales (
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`sale_date` DATETIME,
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`fruit` VARCHAR(7),
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`sold_num` INTEGER
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);
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INSERT INTO Sales
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(`sale_date`, `fruit`, `sold_num`)
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VALUES
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('2020-05-01', 'apples', '10'),
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('2020-05-01', 'oranges', '8'),
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('2020-05-02', 'apples', '15'),
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('2020-05-02', 'oranges', '15'),
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('2020-05-03', 'apples', '20'),
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('2020-05-03', 'oranges', '0'),
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('2020-05-04', 'apples', '15'),
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('2020-05-04', 'oranges', '16');
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---
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**Query #1**
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with cte as (
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select sale_date, sold_num - lead(sold_num) over(partition by sale_date order by sale_date) as diff
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from Sales )
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select * from cte
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where diff is not null;
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| sale_date | diff |
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| ------------------- | ---- |
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| 2020-05-01 00:00:00 | 2 |
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| 2020-05-02 00:00:00 | 0 |
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| 2020-05-03 00:00:00 | 20 |
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| 2020-05-04 00:00:00 | -1 |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/kAcURAmMWtQWMB4dctdbMH/1)

‎Medium/Article Views 2.sql‎

Lines changed: 42 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -45,4 +45,45 @@ select distinct viewer_id as id#, count(distinct article_id) as total
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from views
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group by viewer_id, view_date
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having count(distinct article_id)>1
48-
order by 1
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order by 1
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-- My Solution:
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**Schema (MySQL v8.0)**
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CREATE TABLE Views (
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`article_id` INTEGER,
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`author_id` INTEGER,
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`viewer_id` INTEGER,
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`view_date` DATETIME
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);
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INSERT INTO Views
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(`article_id`, `author_id`, `viewer_id`, `view_date`)
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VALUES
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('1', '3', '5', '2019-08-01'),
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('3', '4', '5', '2019-08-01'),
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('1', '3', '6', '2019-08-02'),
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('2', '7', '7', '2019-08-01'),
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('2', '7', '6', '2019-08-02'),
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('4', '7', '1', '2019-07-22'),
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('3', '4', '4', '2019-07-21'),
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('3', '4', '4', '2019-07-21');
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---
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**Query #1**
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select viewer_id
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from Views
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group by viewer_id, view_date
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having count(distinct article_id) > 1
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order by 1;
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| viewer_id |
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| --------- |
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| 5 |
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| 6 |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/5rD5RTwUAwrVMJZu8fADFX/1)

‎Medium/Calculate Salaries.sql‎

Lines changed: 56 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -71,4 +71,59 @@ case when t1.maximum<1000 then t1.sa
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when t1.maximum between 1000 and 10000 then round(t1.sa*.76,0)
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else round(t1.sa*.51,0)
7373
end as salary
74-
from t1
74+
from t1
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-- My Solution:
77+
**Schema (MySQL v8.0)**
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CREATE TABLE Salaries (
80+
`company_id` INTEGER,
81+
`employee_id` INTEGER,
82+
`employee_name` VARCHAR(11),
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`salary` INTEGER
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);
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INSERT INTO Salaries
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(`company_id`, `employee_id`, `employee_name`, `salary`)
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VALUES
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('1', '1', 'Tony', '2000'),
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('1', '2', 'Pronub', '21300'),
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('1', '3', 'Tyrrox', '10800'),
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('2', '1', 'Pam', '300'),
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('2', '7', 'Bassem', '450'),
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('2', '9', 'Hermione', '700'),
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('3', '7', 'Bocaben', '100'),
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('3', '2', 'Ognjen', '2200'),
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('3', '13', 'Nyancat', '3300'),
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('3', '15', 'Morninngcat', '1866');
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---
101+
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**Query #1**
103+
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with cte as
105+
(select company_id, max(salary) as max_sal from Salaries
106+
group by company_id)
107+
108+
select s.company_id, s.employee_id, s.employee_name, round((case when cte.max_sal < 1000 then s.salary
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when cte.max_sal between 1000 and 10000 then s.salary - (24/100) * s.salary
110+
when cte.max_sal > 10000 then s.salary - (49/100) * s.salary end)) as salary
111+
from Salaries s left join cte
112+
on s.company_id = cte.company_id;
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| company_id | employee_id | employee_name | salary |
115+
| ---------- | ----------- | ------------- | ------ |
116+
| 1 | 1 | Tony | 1020 |
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| 1 | 2 | Pronub | 10863 |
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| 1 | 3 | Tyrrox | 5508 |
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| 2 | 1 | Pam | 300 |
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| 2 | 7 | Bassem | 450 |
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| 2 | 9 | Hermione | 700 |
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| 3 | 7 | Bocaben | 76 |
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| 3 | 2 | Ognjen | 1672 |
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| 3 | 13 | Nyancat | 2508 |
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| 3 | 15 | Morninngcat | 1418 |
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---
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[View on DB Fiddle](https://www.db-fiddle.com/f/gdYTR3RBd5P92nxtzygseW/1)

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