Solution:Step 1: Understand INNER JOIN effect on employees and departmentsThe INNER JOIN returns rows where employees.dept_id matches departments.id, so only employees with a valid department appear.Step 2: Analyze query outputThe query selects employee names and their department names for matching

[Solved] Given the tables:employees(id, name, dept_id)departments(id, dept_name)What will this query return?SELECT e.name, d.dept_name FROM employees e INNER JOIN departments d ON e.dept_id = d.id; | PostgreSQL

PostgreSQL - Joins in PostgreSQL

Given the tables:
employees(id, name, dept_id)
departments(id, dept_name)
What will this query return?

SELECT e.name, d.dept_name FROM employees e INNER JOIN departments d ON e.dept_id = d.id;

AAll employees, even if they have no matching department.

BAn error because of alias usage.

CAll departments with employee names, even if no employees exist.

DAll employees with their department names, only if dept_id matches a department id.

Step-by-Step Solution

Solution:

Step 1: Understand INNER JOIN effect on employees and departments
The INNER JOIN returns rows where employees.dept_id matches departments.id, so only employees with a valid department appear.
Step 2: Analyze query output
The query selects employee names and their department names for matching rows only. Employees without a matching department are excluded.
Final Answer:
All employees with their department names, only if dept_id matches a department id. -> Option D
Quick Check:
INNER JOIN filters unmatched rows [OK]

Quick Trick: INNER JOIN shows only matching rows from both tables [OK]

Common Mistakes:

Assuming unmatched employees appear
Confusing aliases causing errors
Thinking departments without employees appear

Master "Joins in PostgreSQL" in PostgreSQL

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

Given the tables:

Step 1: Understand INNER JOIN effect on employees and departments

Step 2: Analyze query output

Final Answer:

Quick Check:

Want More Practice?