[Solved] Which of the following demonstrates a valid subquery syntax in PostgreSQL? — Ans: SELECT name FROM employees WHERE department_id = (SELECT id FROM departments... | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

Which of the following demonstrates a valid subquery syntax in PostgreSQL?

ASELECT name FROM employees WHERE department_id = (SELECT id FROM departments WHERE name = 'HR');

BSELECT name FROM employees WHERE department_id = SELECT id FROM departments WHERE name = 'HR';

CSELECT name FROM employees WHERE department_id IN SELECT id FROM departments WHERE name = 'HR';

DSELECT name FROM employees WHERE department_id = {SELECT id FROM departments WHERE name = 'HR'};

Step-by-Step Solution

Solution:

Step 1: Identify correct subquery syntax
Subqueries must be enclosed in parentheses.
Step 2: Evaluate options
SELECT name FROM employees WHERE department_id = (SELECT id FROM departments WHERE name = 'HR'); correctly uses parentheses around the subquery.
Final Answer:
SELECT name FROM employees WHERE department_id = (SELECT id FROM departments WHERE name = 'HR'); -> Option A
Quick Check:
Subqueries require parentheses [OK]

Quick Trick: Subqueries always need parentheses [OK]

Common Mistakes:

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Which of the following demonstrates a valid subquery syntax in PostgreSQL?