ORDER BY and Result Sorting in SQL
ORDER BY controls the sequence of rows in a query's output. Without it, PostgreSQL makes no guarantee about the order in which rows are returned.
ORDER BY controls the sequence rows come back in.
Without it, SQL returns rows in whatever order it finds convenient. The database doesn't guarantee any particular sequence unless you ask for one, and that order can change between runs as data changes. The moment you need results in a specific order, you add ORDER BY.
This comes up constantly in analyst work. A sales report needs deals from largest to smallest. A customer list needs to be alphabetical. A log needs to be newest first. The underlying data doesn't care about any of that. ORDER BY is you imposing the sequence that matters for the purpose.
Write ORDER BY after FROM and name the column to sort by. SQL defaults to ascending order — smallest first for numbers, A to Z for text:
SELECT name, price
FROM products
ORDER BY price, idThe id after the comma is a tiebreaker. When two products share the same price, SQL uses id to break the tie and produce a consistent order. Multiple sort keys work left to right: sort by the first, use each additional column to resolve ties.
Add DESC to flip the direction:
Most-expensive-first. The id tiebreaker stays ascending by default, keeping the order predictable when prices match.
You can sort by a computed column. Give the expression an alias in SELECT and reference it by name in ORDER BY — this is one of the few places in a query where a SELECT alias can be used:
SELECT name, price * stock_qty AS stock_value
FROM products
ORDER BY stock_value DESC, nameWhen a sort column contains NULL values, SQL puts them at the end in ascending order and at the top in descending order by default. If you need NULLs in a specific position regardless of direction, NULLS LAST or NULLS FIRST makes it explicit:
SELECT name, city
FROM customers
ORDER BY city DESC NULLS LAST, id9 ORDER BY and Result Sorting practice problems
Write a query to return each product's name and price, sorted from the least expensive to the most expensive.
Write a query to return each department's name and office location, listed alphabetically by department name.
Write a query to return each employee's name and hire date, ordered from most recently hired to earliest.
Write a query to return each customer's name, email, and country, grouped visually by country and then alphabetised within each country.
Write a query to return each product's name and stock value, sorted from highest stock value to lowest.
Write a query to return each product's name, category ID, and price.
Write a query to return each order's ID and total amount, ranked from largest order to smallest.
Write a query to return each customer's name and city.
Write a query to return each employee's name and job title, ordered from the most recently hired to the earliest.
These problems are part of the ORDER BY and Result Sorting lesson in SQLMaxx, with instant grading and a worked solution on each.
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