[Solved] Identify the error in this query: SELECT COUNT(price), SUM(price) FROM sales WHERE price = NULL; — Ans: Using '=' to compare with NULL is incorrect | PostgreSQL

PostgreSQL - Aggregate Functions and GROUP BY

Identify the error in this query: SELECT COUNT(price), SUM(price) FROM sales WHERE price = NULL;

AUsing '=' to compare with NULL is incorrect

BCOUNT cannot be used with price column

CSUM cannot be used with price column

DMissing GROUP BY clause

Step-by-Step Solution

Solution:

Step 1: Check NULL comparison
In SQL, NULL cannot be compared with '='; use IS NULL instead.
Step 2: Validate other parts
COUNT and SUM can be used on price; GROUP BY is not required here.
Final Answer:
Using '=' to compare with NULL is incorrect -> Option A
Quick Check:
NULL comparison needs IS NULL [OK]

Quick Trick: Use IS NULL, not = NULL for NULL checks [OK]

Common Mistakes:

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Identify the error in this query: SELECT COUNT(price), SUM(price) FROM sales WHERE price = NULL;