Math in SELECT: the margin of each product

Bayu, the sales manager, is planning a discount strategy. He needs to know how many rupiah of gross profit (margin) each product makes, which is the selling price minus the cost price. A discount must never be bigger than the margin, or the shop loses money.

Task

From the products table, show the columns name, price, cost, and one calculated column that holds price minus cost, named with AS margin. Columns in exactly that order, 16 rows. Any row order is fine.

Databasetokotables & columns are listed in the right panel

Required keywordsAS

Expected result

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Hint 1
In SELECT you can write a formula (called an expression), not just column names. The formula is calculated for every row.
Hint 2
The math operators work like a calculator: +, -, *, /. Give the calculated column a name with AS.
Hint 3
Add price - cost AS ___ as the fourth column, after name, price, cost.

Reveal them one at a time. The last hint nearly gives the answer away.

Give it a try first. The solution unlocks automatically after your first check.

Answer

SELECT name, price, cost, price - cost AS margin
FROM products;

Explanation

price - cost AS margin is calculated row by row: Kopi Arabika Gayo 85000 - 52000 = 33000, Grinder Kopi Manual 275000 - 180000 = 95000, and so on. The margin column only exists in the query result; the table itself does not change.
Things to watch:

Without AS margin, the header becomes the formula text itself (price - cost), which is awkward to read and to use in a report.
Be careful with division. In SQLite, 7 / 2 returns 3 because both numbers are whole numbers. Write 7.0 / 2 (or multiply by 1.0 first) when you need a decimal result, for example when calculating a margin percentage.

SQL· database toko

SELECT name, price, cost
FROM products;

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