[Solved] Identify the error in this query:SELECT sub.name, sub.order_count FROM (SELECT name, COUNT(*) FROM users GROUP BY name) sub; | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

Identify the error in this query:

SELECT sub.name, sub.order_count FROM (SELECT name, COUNT(*) FROM users GROUP BY name) sub;

ANo error, query is correct

BMissing alias for COUNT(*) column

CIncorrect table name 'users'

DSubquery missing parentheses

Step-by-Step Solution

Solution:

Step 1: Check subquery SELECT list
COUNT(*) needs an alias to be referenced outside the subquery.
Step 2: Understand outer query references
Outer query uses sub.order_count, but COUNT(*) column has no alias, causing error.
Final Answer:
Missing alias for COUNT(*) column -> Option B
Quick Check:
Aggregate columns need aliases in subqueries [OK]

Quick Trick: Always alias aggregate columns in subqueries [OK]

Common Mistakes:

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Identify the error in this query: