Readability

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5.6. Readability#

You may have noticed that SQL is not as fussy as other languages such as Python.

SQL does not care about:

  • Letter capitalisations

  • New lines

  • Indentation

For example, these two queries are equivalent.

SELECT item, cost
FROM products
WHERE pricing = 'each' AND cost < 3.00
ORDER BY item
LIMIT 2;

select iTEm, cOst from ProDuctS where pricing = 'each' and cost < 3.00 order by itEm limit 2;

Which one is easier to read?

General SQL convention is to start clauses on new lines, and to capitalise keywords.

A good programming practice is to make sure that your code is readable so that it is easier for you and for other people to understand. It also makes it easier to identify mistakes (bugs) in your code!

5.6.1. Comments#

When you are writing code, it’s always good to have comments! Comments are there to improve the readability of your code and are ignored by the computer.

To add a comment in SQL we use --.

-- This is a comment

You can use the – to add comments to the ends of lines in your SQL queries.

SELECT firstname
FROM customers
ORDER BY firstname; -- default ascending order

Sometimes you might want to add longer comments. In SQL we use /* to begin the comment and */ to end the comment.

For example, we can write a description of our customers table in SQL.

/* The customers table stores the following attributes:
    - id
    - first_name
    - last_name
    - postcode
*/
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