Commission Amount from Deal Value — SELECT in SQL

The problem

Helix Systems' sales manager is generating a commission statement for a recently closed deal. The deal was worth $48,000 and the account manager's commission rate is 7.5%.

Write a query to return the deal value, the commission rate as a decimal, and the commission amount in dollars in one row.

Output:

A single row with three columns, in this order: deal_value, commission_rate, and commission_amount.

Check answerShift Ctrl ↵

Run previews · Check grades

Write a query, then run it to see results here.

Worked solution Try it yourself first

Solution query

SELECT
  48000 AS deal_value,
  0.075 AS commission_rate,
  48000 * 0.075 AS commission_amount

The shape

A percentage stored as its decimal form (0.075) and used directly as a multiplier — the row exposes the deal value, the rate, and the resulting commission as three labeled columns.

Clause by clause

48000 AS deal_value is a labeled integer literal. The deal closed at $48,000 in revenue, and the alias names the column so the row reads in commission-statement form, with each number labeled by its role.
0.075 AS commission_rate is the rate expressed as a decimal: 7.5% written as the number SQL can multiply by. SQL only knows the decimal form.
48000 * 0.075 AS commission_amount is the multiplication: an integer times a decimal, producing 3600.000. The trailing zeroes are the scale PostgreSQL chose by combining the input scales — integer = 0 decimal places, 0.075 = 3 decimal places, so the result carries 3. The dollar value is still $3,600; the extra zeroes carry precision through the operation rather than indicating any rounding.

Why decimal form and not the percentage notation

SQL has no % operator. A rate written as 7.5% is not something the engine can multiply by — there's no syntax for it. So percentages live in queries as their decimal form: 7.5% becomes 0.075, 25% becomes 0.25, and so on. The conversion is just "drop two decimal places."

The same form works in either direction. If a question gives you a decimal rate and asks for the percentage, you multiply by 100. If it gives you a percentage and asks for the resulting amount, you divide the percentage by 100 to get the decimal, then multiply. The decimal is the form SQL works in.

You practiced expressing a percentage as its decimal form (0.075) and using it to scale another value. Decimal-rate-times-quantity is the recurring shape for every percentage calculation in SQL.

Return the deal value, the commission rate as a decimal, and the commission amount in dollars in one row

The shape

Clause by clause

Why decimal form and not the percentage notation

Reading explains SQL. Writing it, over and over with instant feedback, is what makes you fluent.