[Solved] Which of the following is the correct syntax for aliasing tables in a self join? — Ans: SELECT a.id, b.id FROM employees a JOIN employees b ON a.manager_id = b.id | SQL

SQL - INNER JOIN

Which of the following is the correct syntax for aliasing tables in a self join?

ASELECT employees.id, employees.manager_id FROM employees JOIN employees ON employees.manager_id = employees.id

BSELECT a.id, b.id FROM employees a JOIN employees b ON a.manager_id = b.id

CSELECT id, manager_id FROM employees WHERE id = manager_id

DSELECT * FROM employees AS e1, employees AS e2 WHERE e1.id = e2.manager_id

Step-by-Step Solution

Solution:

Step 1: Check alias usage in self join
Aliasing tables with short names like 'a' and 'b' helps distinguish the same table used twice.
Step 2: Verify join condition and syntax
SELECT a.id, b.id FROM employees a JOIN employees b ON a.manager_id = b.id correctly aliases and joins employees on manager_id matching id.
Final Answer:
SELECT a.id, b.id FROM employees a JOIN employees b ON a.manager_id = b.id -> Option B
Quick Check:
Correct alias syntax = SELECT a.id, b.id FROM employees a JOIN employees b ON a.manager_id = b.id [OK]

Quick Trick: Use aliases to differentiate tables in self join [OK]

Common Mistakes:

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Which of the following is the correct syntax for aliasing tables in a self join?