You want to find the total sales, average sales, and number of sales for each product category in a sales table with columns category and amount. Which query correctly combines these aggregates?
hard📝 Application Q15 of 15
SQL - Aggregate Functions
You want to find the total sales, average sales, and number of sales for each product category in a sales table with columns category and amount. Which query correctly combines these aggregates?
ASELECT category, SUM(amount) AND AVG(amount) AND COUNT(*) FROM sales GROUP BY category;
BSELECT SUM(amount), AVG(amount), COUNT(*) FROM sales;
CSELECT category, SUM(amount), AVG(amount), COUNT(*) FROM sales;
DSELECT category, SUM(amount), AVG(amount), COUNT(*) FROM sales GROUP BY category;
Step-by-Step Solution
Solution:
Step 1: Include category in SELECT and GROUP BY
To get aggregates per category, category must be in SELECT and GROUP BY.
Step 2: Combine aggregates with commas
SUM(amount), AVG(amount), COUNT(*) are combined with commas to get totals, averages, and counts.
Final Answer:
SELECT category, SUM(amount), AVG(amount), COUNT(*) FROM sales GROUP BY category; -> Option D
Quick Check:
GROUP BY category with aggregates = SELECT category, SUM(amount), AVG(amount), COUNT(*) FROM sales GROUP BY category; [OK]
Quick Trick:Group by category and list aggregates with commas [OK]
Common Mistakes:
MISTAKES
Missing GROUP BY clause
Using AND instead of commas between aggregates
Not including category in SELECT when grouping
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