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Writer's pictureAmmu Fredy

TRICKY SQL INTERVIEW QUESTION

Amber's conglomerate corporation just acquired some new companies. Each of the companies follows this hierarchy:


Given the table schemas below, write a query to print the company_code, founder name, total number of lead managers, total number of senior managers, total number of managers, and total number of employees. Order your output by ascending company_code. Note:

  • The tables may contain duplicate records.

  • The company_code is string, so the sorting should not be numeric. For example, if the company_codes are C_1, C_2, and C_10, then the ascending company_codes will be C_1, C_10, and C_2.


Input Format The following tables contain company data:

  • Company: The company_code is the code of the company and founder is the founder of the company.


  • Lead_Manager: The lead_manager_code is the code of the lead manager, and the company_code is the code of the working company.



  • Senior_Manager: The senior_manager_code is the code of the senior manager, the lead_manager_code is the code of its lead manager, and the company_code is the code of the working company.


  • Manager: The manager_code is the code of the manager, the senior_manager_code is the code of its senior manager, the lead_manager_code is the code of its lead manager, and the company_code is the code of the working company.


  • Employee: The employee_code is the code of the employee, the manager_code is the code of its manager, the senior_manager_code is the code of its senior manager, the lead_manager_code is the code of its lead manager, and the company_code is the code of the working company.



Sample Output C1 Monika 1 2 1 2

C2 Samantha 1 1 2 2


Even though the question is too big, the answer to this is easy. two things you need to know is

  1. How to join multiple tables

  2. There are duplicate records, so count the unique records

The solution for this problem is :

select company.company_code,company.founder,count(distinct lead_manager.lead_manager_code),count(distinct senior_manager.senior_manager_code),count(distinct manager.manager_code),count(distinct employee.employee_code)

from company join lead_manager on company.company_code =lead_manager.company_code

join senior_manager on company.company_code = senior_manager.company_code

join manager on company.company_code = manager.company_code

join employee on company.company_code = employee.company_code

group by company.company_code,company.founder

order by company.company_code




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