Solution:Step 1: Understand the subquery filtering departmentsThe subquery selects department IDs where the department name is 'Sales'.Step 2: Filter employees by matching department IDsThe main query returns employee names whose department_id matches those IDs.Final Answer:Names of employees who wo

[Solved] Given the tables:employees(id, name, department_id)departments(id, name)What will this query return?SELECT name FROM employees WHERE department_id IN (SELECT id FROM departments WHERE name = 'Sales'); | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

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

SELECT name FROM employees WHERE department_id IN (SELECT id FROM departments WHERE name = 'Sales');

AAn error because subquery returns multiple rows.

BNames of all employees regardless of department.

CNames of employees who do not work in Sales.

DNames of employees who work in the Sales department.

Step-by-Step Solution

Solution:

Step 1: Understand the subquery filtering departments
The subquery selects department IDs where the department name is 'Sales'.
Step 2: Filter employees by matching department IDs
The main query returns employee names whose department_id matches those IDs.
Final Answer:
Names of employees who work in the Sales department. -> Option D
Quick Check:
IN filters employees by Sales department IDs [OK]

Quick Trick: Subquery filters departments, main query filters employees [OK]

Common Mistakes:

Thinking it returns all employees
Confusing NOT IN with IN
Assuming subquery causes error with multiple rows

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Given the tables:

Step 1: Understand the subquery filtering departments

Step 2: Filter employees by matching department IDs

Final Answer:

Quick Check:

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