[Solved] Which of the following is the correct syntax to use a subquery in the FROM clause? — Ans: SELECT * FROM (SELECT id, name FROM users) AS u; | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

Which of the following is the correct syntax to use a subquery in the FROM clause?

ASELECT * FROM users WHERE (SELECT id FROM orders);

BSELECT * FROM (SELECT id, name FROM users) AS u;

CSELECT * FROM users JOIN (SELECT id FROM orders);

DSELECT * FROM users (SELECT id FROM orders) AS o;

Step-by-Step Solution

Solution:

Step 1: Identify correct subquery syntax in FROM
The subquery must be enclosed in parentheses and given an alias.
Step 2: Check each option
SELECT * FROM (SELECT id, name FROM users) AS u; correctly uses parentheses and alias AS u. Others have syntax errors or missing alias.
Final Answer:
SELECT * FROM (SELECT id, name FROM users) AS u; -> Option B
Quick Check:
Correct syntax = SELECT * FROM (SELECT id, name FROM users) AS u; [OK]

Quick Trick: Subquery in FROM needs parentheses and alias [OK]

Common Mistakes:

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Which of the following is the correct syntax to use a subquery in the FROM clause?