refactor 178, 181 and 183

Author: fishercoder1534

database/_178.sql

@@ -1,29 +1,3 @@
--- Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking number should be the next consecutive integer value. In other words, there should be no "holes" between ranks.
---
--- +----+-------+
--- | Id | Score |
--- +----+-------+
--- | 1  | 3.50  |
--- | 2  | 3.65  |
--- | 3  | 4.00  |
--- | 4  | 3.85  |
--- | 5  | 4.00  |
--- | 6  | 3.65  |
--- +----+-------+
--- For example, given the above Scores table, your query should generate the following report (order by highest score):
---
--- +-------+------+
--- | Score | Rank |
--- +-------+------+
--- | 4.00  | 1    |
--- | 4.00  | 1    |
--- | 3.85  | 2    |
--- | 3.65  | 3    |
--- | 3.65  | 3    |
--- | 3.50  | 4    |
--- +-------+------+
-
--- # Write your MySQL query statement below
 select Score,
     (select count(distinct Score) from Scores where Score >= s.Score) Rank
 from Scores s

database/_181.sql

@@ -1,2 +1 @@
--- Write your MySQL query statement below
 select e.Name as Employee from Employee e left join Employee b on e.ManagerId = b.Id where e.Salary > b.Salary;

database/_183.sql

@@ -1,30 +1 @@
--- Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything.
---
--- Table: Customers.
---
--- +----+-------+
--- | Id | Name  |
--- +----+-------+
--- | 1  | Joe   |
--- | 2  | Henry |
--- | 3  | Sam   |
--- | 4  | Max   |
--- +----+-------+
--- Table: Orders.
---
--- +----+------------+
--- | Id | CustomerId |
--- +----+------------+
--- | 1  | 3          |
--- | 2  | 1          |
--- +----+------------+
--- Using the above tables as example, return the following:
---
--- +-----------+
--- | Customers |
--- +-----------+
--- | Henry     |
--- | Max       |
--- +-----------+
-
 select Name as Customers from Customers left join Orders on Customers.Id = Orders.CustomerId where Orders.CustomerId is Null;