Lesson 9.4

Formatting SQL Queries for Readability

Clean formatting doesn't change what a query returns, but it makes mistakes far easier to spot.

A query crammed onto one line still runs, but good luck spotting the bug in it. Formatting is a debugging tool: when each clause sits on its own line, a missing comma or a misplaced condition jumps out.

The habits are simple: one column per line, each clause (FROM, JOIN, GROUP BY) starting a new line, the join condition indented under its JOIN, and clear aliases. Pure formatting should preserve the query's meaning while making that meaning easier to inspect.

Pattern

select col_a,
       col_b,
       count(*) as n
from table_one as t
join table_two as u
  on t.id = u.t_id
group by col_a, col_b
order by n desc

Syntax reference

Need the rules? See the SQL query formatting guide

Schema · Garden Shop Tables · customers, orders 2 tables

Table · customers

One row per customer. Some customers have no phone on file.

9 columns · 20 rows

customer_id int first_name text last_name text email text phone text city text state text signup_date date is_active bool

Table · orders

One row per order. Unshipped orders have a null shipped_date.

6 columns · 24 rows

order_id int customer_id int order_date date shipped_date date status text coupon_code text

Your task

The starter is a correct query crammed onto a single line. Reformat it for readability. It should still return each customer's first_name, last_name, and order count as orders, most orders first. The rows won't change; only the layout will.