Question

SQL seems to be the most neglected language when it comes to formatting nicely and readably… And as SQL statements can be incredibly detailed and complex, it makes it extremely hard to work with. But I find that when I try to format my SQL code in the best way possible I’m sometimes unsure of how to do it. I know the standards for Java, C#, Python, etc…. but when it comes to SQL I haven’t seen too many guidelines or accepted practices. What are tips/rules for formatting SQL so that it’s clear, legible, and logical? Can you give example code to illustrate? What have you found to be the most standard, accepted way of formatting SQL?

Answer 1

You could try checking out Joe Celko’s book SQL Programming Style. I’m sure that there are a lot of people who disagree with his style, but it’s a good start.

Some of my own “rules”

• SQL keywords are always all upper-case
• Table names are “proper” case, while columns and variables are all lower-case
• Each “major” clause in a statement is at the start of a line
• JOIN and WHERE criteria appear beneath and are indented and aligned
• Nested items are indented further
• I use aliases for all tables and views

For example:

SELECT
    column_1,
    column_2,
    CASE
        WHEN column_5 = 'Blah' THEN 1
        WHEN column_6 = 'Blah' THEN 2
        ELSE 3
    END AS column_alias
FROM
    My_Table MT
INNER JOIN My_Other_Table MOT ON
    MOT.column_1 = MT.column_1
WHERE
    MT.column_2 = 'Some Value' AND
    (
        MT.column_3 = 'Some other value' OR
        MT.column_4 = 'Some other value'
    )