MySQL Solution for Employees with Missing Information Problem
Intuition\r\n Describe your first thoughts on how to solve this problem. \r\nThe goal is to find the employee IDs for which either the name or the salary inform
# Intuition\r\n<!-- Describe your first thoughts on how to solve this problem. -->\r\nThe goal is to find the employee IDs for which either the name or the salary information is missing. We can achieve this by performing a combination of LEFT JOIN and RIGHT JOIN between the Employees and Salaries tables and then filtering the rows where the name or salary is NULL.\r\n\r\n# Approach\r\n<!-- Describe your approach to solving the problem. -->\r\n1. Perform a LEFT JOIN between the Employees and Salaries tables to get all rows from the Employees table and matching rows from the Salaries table based on the employee_id.\r\n1. In the WHERE clause, filter the rows where the name from the Employees table is NULL or the salary from the Salaries table is NULL. This will give us the employee IDs for which either the name or salary information is missing.\r\n1. Perform a RIGHT JOIN between the Employees and Salaries tables to get all rows from the Salaries table and matching rows from the Employees table based on the employee_id.\r\n1. In the WHERE clause, filter the rows where the name from the Employees table is NULL or the salary from the Salaries table is NULL. This will give us additional employee IDs for which either the name or salary information is missing.\r\n1. Use the UNION operator to combine the results of both joins to get the final set of employee IDs with missing information.\r\n1. Sort the employee IDs in ascending order using ORDER BY.\r\n\r\n# Complexity\r\n- Time complexity:\r\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\r\nThe time complexity of the SQL query is O(n + m), where n is the number of rows in the Employees table and m is the number of rows in the Salaries table. This is because we need to perform two joins, one for each table, and then filter the rows based on the WHERE clause.\r\n\r\n- Space complexity:\r\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\r\nThe space complexity is O(max(n, m)), where n is the number of rows in the Employees table and m is the number of rows in the Salaries table. This is because the space required to store the results of the two joins and the UNION operation depends on the maximum number of rows between the two tables.\r\n\r\n# Code\r\n```\r\n# Write your MySQL query statement below\r\nSELECT COALESCE(e.employee_id, s.employee_id) AS employee_id\r\nFROM Employees e\r\nLEFT JOIN Salaries s ON e.employee_id = s.employee_id\r\nWHERE e.name IS NULL OR s.salary IS NULL\r\n\r\nUNION\r\n\r\nSELECT COALESCE(e.employee_id, s.employee_id) AS employee_id\r\nFROM Employees e\r\nRIGHT JOIN Salaries s ON e.employee_id = s.employee_id\r\nWHERE e.name IS NULL OR s.salary IS NULL\r\n\r\nORDER BY employee_id;\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n```
['MySQL']