Are there any published coding style guidelines for SQL?

Question

Often I will end up with very complex SQL statements and I wondered if there was style guideline out there that dictates a common way of laying various aspects of a query out.

Answer 1

Kickstarter has a style guide here. I have a modified version of that for people who prefer lowercase SQL and Celko's "river".

My style guide is here. Here is a sample:

-- basic select example
select p.Name as ProductName
     , p.ProductNumber
     , pm.Name as ProductModelName
     , p.Color
     , p.ListPrice
  from Production.Product as p
  join Production.ProductModel as pm
    on p.ProductModelID = pm.ProductModelID
 where p.Color in ('Blue', 'Red')
   and p.ListPrice < 800.00
   and pm.Name like '%frame%'
 order by p.Name

-- basic insert example
insert into Sales.Currency (
    CurrencyCode
    ,Name
    ,ModifiedDate
)
values (
    'XBT'
    ,'Bitcoin'
    ,getutcdate()
)

-- basic update example
update p
   set p.ListPrice = p.ListPrice * 1.05
     , p.ModifiedDate = getutcdate()
  from Production.Product as p
 where p.SellEndDate is null
   and p.SellStartDate is not null

-- basic delete example
delete cc
  from Sales.CreditCard as cc
 where cc.ExpYear < '2003'
   and cc.ModifiedDate < dateadd(year, -1, getutcdate())

Answer 2

Since asking this question I have written a public SQL style guide that is compatible with Joe Celko's SQL Programming Style book under the Creative Commons Attribution-ShareAlike licence.

It is available over at www.sqlstyle.guide or as markdown directly from the GitHub repo.

Answer 3

Have you thought about getting your team to use a tool with built in formatting capabilities?Toad for MySql has this. Its not going be a guide as such but a least will bring some consistency.

Answer 4

Here are some SQL programming guidelines and best practices we collected:

• Do not use SELECT * in your queries.
• Always use table aliases when your SQL statement involves more than one source.
• Use the more readable ANSI-Standard Join clauses instead of the old style joins.
• Do not use column numbers in the ORDER BY clause.
• Always use a column list in your INSERT statements.
• Don't ever use double quotes in your T-SQL code.
• Do not prefix your stored procedure names with “sp_”.
• Always use a SQL formatter to format your SQL like Instant SQL Formatter (free and online)

You can check detailed explanation of those best practices in this blog post.

Answer 5

MySQL has a short description of their more or less strict rules:

https://dev.mysql.com/doc/internals/en/coding-style.html

Most common codingstyle for MySQL by Simon Holywell:

http://www.sqlstyle.guide/

See also this question: Is there a naming convention for MySQL?

Answer 6

Two guides I know of are Joe Celko's SQL Programming Style and the venerable Code Complete.

There's also the SQL-92 standard. It doesn't contain a style section, but you might consider it's style to be implicitly canonical.