task: solution task #584 leetcode

Author: yuri-isaev

tasks/leetcode/570_managers_with_at_least_5_direct_reports.sql

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+-- Задача 570.
+-- Напишите SQL-запрос, чтобы сообщить менеджерам, по крайней мере, с пятью прямыми подчиненными.
+-- Вывести: таблицу результатов в любом порядке.
+
+USE leetcode
+
+IF EXISTS(SELECT *
+          FROM INFORMATION_SCHEMA.TABLES
+          WHERE TABLE_NAME = N'Employee')
+    BEGIN
+        DROP TABLE Employee
+        PRINT 'Table delete successfully'
+    END
+ELSE
+    BEGIN
+        CREATE TABLE Employee
+        (
+            id         int,
+            name       varchar(255),
+            department varchar(255),
+            managerId  int
+        )
+
+        INSERT INTO Employee (id, name, department, managerId) VALUES (101, 'John', 'A', null)
+        INSERT INTO Employee (id, name, department, managerId) VALUES (102, 'Dan', 'A', 101)
+        INSERT INTO Employee (id, name, department, managerId) VALUES (103, 'James', 'A', 101)
+        INSERT INTO Employee (id, name, department, managerId) VALUES (104, 'Amy', 'A', 101)
+        INSERT INTO Employee (id, name, department, managerId) VALUES (105, 'Anne', 'A', 101)
+        INSERT INTO Employee (id, name, department, managerId) VALUES (106, 'Ron', 'B', 101)
+
+        PRINT 'Table create successfully'
+    END
+GO
+
+-- Solution
+SELECT
+    e1.name
+FROM
+    Employee e1
+         INNER JOIN
+    Employee e2
+        ON
+         e1.id = e2.managerId
+GROUP BY
+    e1.name
+HAVING
+    COUNT(e1.name) >= 5
+GO
+
+-- Solution
+SELECT
+    e.name
+FROM
+    Employee e
+WHERE (SELECT
+           COUNT(managerId)
+       FROM
+           Employee
+       WHERE
+           managerId = e.id) >= 5
+GO
+
+
+-- Input:
+-- Employee table:
++-----+-------+------------+-----------+
+| id  | name  | department | managerId |
++-----+-------+------------+-----------+
+| 101 | John  |     A      |   None    |
+| 102 | Dan   |     A      |   101     |
+| 103 | James |     A      |   101     |
+| 104 | Amy   |     A      |   101     |
+| 105 | Anne  |     A      |   101     |
+| 106 | Ron   |     B      |   101     |
++-----+-------+------------+-----------+
+
+-- Output:
++------+
+| name |
++------+
+| John |
++------+

tasks/leetcode/584_find_customer_referee.sql

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+-- Задача 570.
+-- Напишите SQL-запрос, чтобы сообщить имена клиентов, на которые клиент не ссылается с помощью.
+-- id = 2
+-- Вывести: таблицу результатов в любом порядке.
+
+USE leetcode
+
+IF EXISTS(SELECT *
+          FROM INFORMATION_SCHEMA.TABLES
+          WHERE TABLE_NAME = N'Customer')
+    BEGIN
+        DROP TABLE Customer
+        PRINT 'Table delete successfully'
+    END
+ELSE
+    BEGIN
+        CREATE TABLE Customer
+        (
+            id         int,
+            name       varchar(25),
+            referee_id int
+        )
+
+        INSERT INTO Customer (id, name, referee_id) VALUES (1, 'Will', null)
+        INSERT INTO Customer (id, name, referee_id) VALUES (2, 'Jane', null)
+        INSERT INTO Customer (id, name, referee_id) VALUES (3, 'Alex', 2)
+        INSERT INTO Customer (id, name, referee_id) VALUES (4, 'Bill', null)
+        INSERT INTO Customer (id, name, referee_id) VALUES (5, 'Zack', 1)
+        INSERT INTO Customer (id, name, referee_id) VALUES (6, 'Mark', 2)
+
+        PRINT 'Table create successfully'
+    END
+GO
+
+-- Solution
+SELECT
+    name
+FROM
+    Customer
+WHERE
+    referee_id IS NULL
+   OR
+    referee_id <> 2
+GO
+
+-- Solution
+SELECT
+    name
+FROM
+    Customer
+WHERE
+    referee_id != 2
+   OR
+    referee_id IS NULL
+GO
+
+-- Solution
+SELECT
+    name
+FROM
+    Customer
+WHERE
+    isnull(referee_id, 0) != 2
+GO
+
+
+-- Input:
+-- Customer table:
++----+------+------------+
+| id | name | referee_id |
++----+------+------------+
+| 1  | Will | null       |
+| 2  | Jane | null       |
+| 3  | Alex | 2          |
+| 4  | Bill | null       |
+| 5  | Zack | 1          |
+| 6  | Mark | 2          |
++----+------+------------+
+
+-- Output:
++------+
+| name |
++------+
+| Will |
+| Jane |
+| Bill |
+| Zack |
++------+