[Solved] Which of the following shows the correct way to use a nested subquery in the FROM clause? — Ans: SELECT emp_id FROM (SELECT emp_id FROM Employees WHERE dept_id = 10) AS... | SQL

SQL - Subqueries

Which of the following shows the correct way to use a nested subquery in the FROM clause?

ASELECT emp_id FROM (SELECT emp_id FROM Employees WHERE dept_id = 10) AS DeptEmployees;

BSELECT emp_id FROM Employees WHERE dept_id = SELECT dept_id FROM Departments WHERE name = 'HR';

CSELECT emp_id FROM Employees WHERE dept_id IN SELECT dept_id FROM Departments;

DSELECT emp_id FROM Employees WHERE dept_id = (SELECT dept_id FROM Departments WHERE name = 'HR'

Step-by-Step Solution

Solution:

Step 1: Identify correct nested subquery syntax in FROM clause
Nested subqueries in FROM require aliasing the subquery result.
Step 2: Analyze options
SELECT emp_id FROM (SELECT emp_id FROM Employees WHERE dept_id = 10) AS DeptEmployees; correctly uses parentheses and alias 'AS DeptEmployees'. Others have syntax errors or missing parentheses.
Final Answer:
Option A -> Option A
Quick Check:
Subquery in FROM must be aliased [OK]

Quick Trick: Always alias subqueries in FROM clause [OK]

Common Mistakes:

MISTAKES

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Which of the following shows the correct way to use a nested subquery in the FROM clause?