Given an employees table with columns id, name, and manager_id, which SQL query correctly lists each employee's name alongside their manager's name using a self join?
easy📝 Syntax Q3 of 15
SQL - Advanced Joins
Given an employees table with columns id, name, and manager_id, which SQL query correctly lists each employee's name alongside their manager's name using a self join?
ASELECT e.name, m.name AS manager_name FROM employees e JOIN employees m ON e.id = m.id;
BSELECT e.name, m.name AS manager_name FROM employees e JOIN employees m ON e.id = m.manager_id;
CSELECT e.name, m.name AS manager_name FROM employees e JOIN employees m ON e.manager_id = m.manager_id;
DSELECT e.name, m.name AS manager_name FROM employees e JOIN employees m ON e.manager_id = m.id;
Step-by-Step Solution
Solution:
Step 1: Understand the relationship
The manager_id in the employee row refers to the id of their manager.
Step 2: Use self join on correct keys
Join employees e with employees m where e.manager_id = m.id to get manager's name.
Final Answer:
SELECT e.name, m.name AS manager_name FROM employees e JOIN employees m ON e.manager_id = m.id; -> Option D
Quick Check:
Manager's id matches employee's manager_id [OK]
Quick Trick:Join on employee.manager_id = manager.id [OK]
Common Mistakes:
MISTAKES
Joining on employee.id = manager.manager_id reverses the relationship
Joining on manager_id = manager_id compares wrong columns
Joining on employee.id = manager.id returns only same employees
Master "Advanced Joins" in SQL
9 interactive learning modes - each teaches the same concept differently
