SQLMaxx
Sign in Start free
N011-E2 Tier 1 · Foundations · easy

Return the total licensing cost in a single column named `total_cost`

Part of Arithmetic and Comparison Expressions in SQL

The problem

Helix Systems' IT procurement team is budgeting for a software licence renewal. The licence carries a $500 flat fee plus $12 per user seat, and the team has 9 users.

Write a query to return the total licensing cost in a single column named total_cost.

Output:

  • A single row with one column, total_cost, containing the combined fixed-plus-variable total.
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
  500 + 12 * 9 AS total_cost

The shape

Multiplication binds tighter than addition, so 12 * 9 resolves first to the variable per-seat cost and the flat $500 fee is added on top — no parentheses needed.

Clause by clause

  • SELECT 500 + 12 * 9 evaluates the multiplication first because of standard arithmetic precedence: 12 * 9 returns 108, the per-seat cost for nine users, and then 500 + 108 returns 608. All three operands are integers, so the result is the integer 608 — the total licensing cost in whole dollars.
  • AS total_cost labels the column so the result reads as a budget line item. The procurement team can drop the value straight into the renewal sheet without renaming anything after the fact.

Why this and not (500 + 12) * 9

Parenthesising the addition changes the calculation entirely. (500 + 12) * 9 returns 4608, which would be the total if every user were charged for the flat fee plus one seat. That's not the pricing model; the flat fee is paid once and the per-seat cost is variable. Standard operator precedence already groups fixed + rate * quantity the way the business logic wants it grouped, so no parentheses are needed here.

You practiced relying on standard operator precedence — multiplication binds tighter than addition, so 500 + 12 * 9 evaluates the per-user piece first, then adds the flat fee. The shape recurs whenever a calculation has both a fixed cost and a per-unit cost.

How you actually get good at SQL

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

That's the whole SQLMaxx loop: 600+ real problems, instant AI feedback, mastery you can actually see, and spaced review that won't let you forget.

A stack of SQL practice problem cards, the top card showing an employees table.
615 problems · 66 concepts

Real problems. Not toy examples.

615 hand-built problems spanning all 66 concepts, from basic SELECTs to window functions, built on real schemas and real business questions, the kind you'll actually get asked on the job. Enough reps to make SQL automatic.

A retro computer showing a SQL query marked correct with a green checkmark.
Instant AI feedback

Write a query. Know if it's right in one second.

No copying an answer and hoping it clicked. The AI grader checks your real query against real data, catches exactly what's wrong, and explains the fix in plain English, like a senior analyst reading over your shoulder on every problem.

A circular mastery progress dial filling from blue to green, the SQLMaxx diamond at its center.
Mastery tracking

Stop guessing whether you actually know it.

SQLMaxx tracks every concept and shows you what you've mastered and what's still shaky. Your skills fill in one concept at a time, so 'I think I get joins' becomes something you can prove.

A SQL query editor circled by a blue return arrow with a clock, scheduled to come back for review.
Spaced review

Learn it once. Keep it for good.

Most of what you learn this week fades by next week. So when a concept comes due for review, SQLMaxx hands you a fresh problem to solve from a blank editor, not a flashcard to re-read. A research-backed spaced-repetition algorithm (FSRS) times each return for right before you'd forget, so your SQL is still there months later, when the interview or the job actually needs it.

Practice, feedback, mastery, review. That's the loop that turns reading into real skill.

Start free

No account, no credit card. Start solving in under a minute.