[Solved] You have a table products with 100 rows. The price column has 10... What does this query return?SELECT COUNT(*) AS total_rows, COUNT(price) AS price_count, COUNT(stock) AS stock_count FROM products; | SQL

SQL - Aggregate Functions

You have a table products with 100 rows. The price column has 10 NULLs and the stock column has 5 NULLs. What does this query return?
SELECT COUNT(*) AS total_rows, COUNT(price) AS price_count, COUNT(stock) AS stock_count FROM products;

Atotal_rows=100, price_count=100, stock_count=100

Btotal_rows=95, price_count=90, stock_count=95

Ctotal_rows=100, price_count=90, stock_count=95

Dtotal_rows=90, price_count=90, stock_count=95

Step-by-Step Solution

Solution:

Step 1: Understand COUNT(*)
COUNT(*) counts all rows: 100.
Step 2: Calculate COUNT(price)
price has 10 NULLs, so count is 100 - 10 = 90.
Step 3: Calculate COUNT(stock)
stock has 5 NULLs, so count is 100 - 5 = 95.
Final Answer:
total_rows=100, price_count=90, stock_count=95 -> Option C
Quick Check:
COUNT(*) counts all; COUNT(column) excludes NULLs [OK]

Quick Trick: COUNT(*) counts all rows; COUNT(column) excludes NULLs [OK]

Common Mistakes:

MISTAKES

Subtracting NULLs incorrectly
Assuming COUNT(column) counts NULLs
Mixing total rows with column counts

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More SQL Quizzes

You have a table products with 100 rows. The price column has 10 NULLs and the stock column has 5 NULLs. What does this query return?

Step 1: Understand COUNT(*)

Step 2: Calculate COUNT(price)

Step 3: Calculate COUNT(stock)

Final Answer:

Quick Check:

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