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This approach utilizes a subquery within a NOT EXISTS condition to identify salespersons who have not placed any orders for the company named 'RED'. By leveraging the NOT EXISTS, we can efficiently filter out salespersons who are not involved with any orders corresponding to 'RED'.
Time Complexity: O(N * M), where N is the number of salespersons and M is the number of orders.
Space Complexity: O(1), since we are using in-DB operations without additional data structures.
1SELECT name FROM SalesPerson WHERE NOT EXISTS (SELECT 1 FROM Orders o JOIN Company c ON o.com_id = c.com_id WHERE c.name = 'RED' AND o.sales_id = SalesPerson.sales_id)The above SQL query selects all salespersons from the SalesPerson table who do not exist in the subquery result. The subquery joins the Orders and Company tables, filtering for orders related to the company named 'RED'. The NOT EXISTS clause excludes salespersons who have orders related to 'RED'.
This approach involves performing a LEFT JOIN operation between the SalesPerson and Orders tables, filtering orders related to 'RED', and then checking for NULLs to identify salespersons with no such orders. This exploits the fact that when a LEFT JOIN does not find matches, the result will have NULL entries.
Time Complexity: O(N + M), where N is the number of salespersons and M is the number of companies/orders.
Space Complexity: O(1), as operations occur within the database without additional data structure utilization.
1SELECT s.name FROM SalesPerson s LEFT JOIN Orders o ON s.sales_id = o.sales_id LEFT JOINThis approach involves using INNER JOIN to identify the salespersons who have placed orders for the company named RED. Then, with a subquery and GROUP BY, we identify all salespersons with no association with RED by excluding them from the full list of salespersons.
Time Complexity: O(n + m + k) where n, m, and k are the number of rows in SalesPerson, Orders, and Company tables respectively.
Space Complexity: O(n).
1SELECT name FROM SalesPerson WHERE sales_id NOT IN ( SELECT DISTINCT sales_id FROM Orders INNER JOIN Company This approach exploits the LEFT JOIN feature to link salespersons with orders related to the company RED. We then filter out the entries where no such orders exist, effectively capturing the desired salespersons.
Time Complexity: O(n * log m) where n and m are the number of rows in SalesPerson and Orders tables respectively.
Space Complexity: O(n).
1SELECT sp.name FROM SalesPerson sp LEFT JOIN Orders o ON sp.sales_id = o.sales_id LEFT JOIN Company c ONThis SQL query first performs a LEFT JOIN between the SalesPerson, Orders, and Company tables. With the condition filtering for company name 'RED', salespersons without related orders will result in NULL for the company columns. The WHERE clause checks for these NULL entries, effectively excluding salespersons with orders for 'RED'.
This SQL query does the following:
- It retrieves all salesperson names from the SalesPerson table.
- Excludes those who have made orders for the company RED by using a subquery.
- The subquery joins the Orders and Company tables to find the sales_id of orders made to RED.
- The use of NOT IN excludes these salespeople from the final list.
The solution works as follows:
- Perform a LEFT JOIN between SalesPerson and Orders tables based on sales_id.
- Apply a second LEFT JOIN with the Company table filtered for the name RED.
- Finally, filter on c.com_id IS NULL to find salespersons without orders to the company RED.