Mechanical Data Analyst

180 .  Consecutive Numbers   Hello All, I am back with another SQL leetcode solution. This time we are going one step ahead and practice question with medium difficulty. SQL Schema Table:  Logs +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | num | varchar | +-------------+---------+ id is the primary key for this table. id is an autoincrement column.   Write an SQL query to find all numbers that appear at least three times consecutively. Return the result table in  any order . The query result format is in the following example.   Example 1: Input: Logs table: +----+-----+ | id | num | +----+-----+ | 1 | 1 | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 1 | | 6 | 2 | | 7 | 2 | +----+-----+ Output: +-----------------+ | ConsecutiveNums | +-----------------+ | 1 | +-----------------+ Explanation: 1 is the only number that appears consecutively for at least three ti...

Leetcode question no. 181   181 .  Employees Earning More Than Their Managers SQL Schema Table:  Employee +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | | salary | int | | managerId | int | +-------------+---------+ id is the primary key column for this table. Each row of this table indicates the ID of an employee, their name, salary, and the ID of their manager.   Write an SQL query to find the employees who earn more than their managers. Return the result table in  any order . The query result format is in the following example.   Example 1: Input: Employee table: +----+-------+--------+-----------+ | id | name | salary | managerId | +----+-------+--------+-----------+ | 1 | Joe | 70000 | 3 | | 2 | Henry | 80000 | 4 | | 3 | Sam | 60000 | Null | | 4 | Max | 90000 | Null | +----+-------+--------+-----------+ Output: ...

  182 .  Duplicate Emails SQL Schema Table:  Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | email | varchar | +-------------+---------+ id is the primary key column for this table. Each row of this table contains an email. The emails will not contain uppercase letters.   Write an SQL query to report all the duplicate emails. Return the result table in  any order . The query result format is in the following example.   Example 1: Input: Person table: +----+---------+ | id | email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ Output: +---------+ | Email | +---------+ | a@b.com | +---------+ Explanation: a@b.com is repeated two times. Solution : # Write your MySQL query statement below select Email from Person group by Email having count(Email) > 1; Approach : First Approach is finding out count of each email address 1) # Write your MySQ...

Answer to SQL Leetcode Question 183 183 .  Customers Who Never Order   SQL Schema Table:  Customers +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | +-------------+---------+ id is the primary key column for this table. Each row of this table indicates the ID and name of a customer.   Table:  Orders +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | customerId | int | +-------------+------+ id is the primary key column for this table. customerId is a foreign key of the ID from the Customers table. Each row of this table indicates the ID of an order and the ID of the customer who ordered it.   Write an SQL query to report all customers who never order anything. Return the result table in  any order . The query result format is in the following example.   Example 1: Input: Customers table: +----+-------+ | id | name | +---...