What does SQL clause "GROUP BY 1" mean?

The convenience and pitfalls of ordinal notation in SQL

In short, GROUP BY 1 is a concise and flexible SQL feature that directly refers to the order of columns in the SELECT statement, not their names. If you're prone to frequent and dynamic column name changes, this method will save your sanity... and a few keystrokes.

Perks of ordinal positions

• Lean syntax: Faster, less convoluted query writing.
• Refactor-friendly: Queue the sighs of relief. While changing column names, the GROUP BY clause remains oblivious.
• Less is more: The query is more focused on column order, side-stepping verbose or complex column names.

A word of caution

Ordinal positioning isn't all sunshine and roses. A couple of potential drawbacks include:

• Refactor roulette: If the column order changes, your GROUP BY could easily group the wrong field. Oops.
• WTF moments: To an unfamiliar developer, this numeric notation can be cryptic.
• Debugging demon: Explicit column names make bug-hunting easier, particularly for extensive data sets.

Best practice tips

To avoid shaking your fist at SQL, reserve GROUP BY 1 for times when your query is less likely to experience refactoring. It's perfect when you need a quick data snapshot, are running one-off reports or are working in a data analysis notebook.

GROUP BY 1: Efficiency at a price

Take a look at this practical example of how quick refactoring can cause heartburn:

-- The dev plans to shake hands with 'city' in a crowd via:
SELECT city, country, COUNT(*)
FROM customers
GROUP BY 1;

-- The cruel hand of refactor waves its magic wand, and now it's awkwardly patting 'country' on the back:
SELECT country, city, COUNT(*)
FROM customers
GROUP BY 1; -- Hey country, didn't see you there!


This example illustrates the key point: GROUP BY 1 is a fast-track solution, but check your rearview mirror for unintended results!

Order in the court: Enter ORDER BY 1

To orderly align your data, ORDER BY 1 is a perfect pairing with GROUP BY 1, ensuring your sorted data is grouped and courteously arranged by the same column. Perfect for when the presentation is as crucial as the data itself.

Harmony between GROUP BY and ORDER BY

• A place for everything: Grouped data follows an orderly line.
• Economy of scanning: Ordered data is simpler to digest.
• Performance boost: Databases love it when they know the data order upfront.

ORDER BY: the party organizer

Think of ORDER BY 1 as appointing a top-notch party planner who directs guests to sit in order of their main dish. Say hello to an organized audience at your data banquet!