Avoid the use of

CamelCase—it is difficult to scan quickly
Descriptive prefixes or Hungarian notation such as sp_ or tbl
Plurals—use the more natural collective term instead
Quoted identifiers—if you must use them then stick to SQL92 double quotes for portability

{% highlight sql %}{% include sql/naming_conventions.sql %}{% endhighlight %}

Reserved words

Always use uppercase for the reserved keywords like SELECT and WHERE.

It is best to avoid the abbreviated keywords and use the full length ones where available (prefer ABSOLUTE to ABS).

Do not use database server specific keywords where an ANSI SQL keyword already exists performing the same function. This helps to make code more portable.

{% highlight sql %}{% include sql/syntax_reserved_keywords.sql %}{% endhighlight %}

Indentation

Use four (4) spaces all the way through all the time. This makes the most sense where there is a sub query.

{% highlight sql %}{% include sql/syntax_indentation.sql %}{% endhighlight %}

White space

To make the code easier to read it is important that the correct compliment of spaces is used. Do not crowd code or remove natural spaces.

Always include spaces (this is not an exhaustive list):

before and after equals (=)
after commas (,)
surrounding apostrophes (') where not within parentheses or with a trailing comma or semicolon

Always include newlines/vertical space:

after semicolons to separate queries for easier reading
after each keyword definition
after the comma of each column in the list
before AND or OR

Keeping all the keywords aligned to the righthand side and the values left aligned creates a uniform gap down the middle of query. It makes it much easier to scan the query definition over quickly too.

{% highlight sql %}{% include sql/syntax_spacing.sql %}{% endhighlight %}

General

Ensure the name is unique and does not exist as a reserved keyword
Keep the length to a maximum of 30 bytes—in practice this is 30 characters unless you are using multibyte charset
Names must begin with a letter and may not end with an underscore
Only use letters, numbers and underscores in names
Avoid the use of multiple consecutive underscores—these can be hard to read
Use underscores where you would naturally include a space in name (first name becomes first_name)
Avoid abbreviations and if you have to use them make sure they are commonly understood

{% highlight sql %}{% include sql/naming_conventions.sql %}{% endhighlight %}

Tables

Use a collective name or, less ideally, a plural form. For example (in order of preference) staff and employees.
Do not prefix with tbl or any other such descriptive prefix or Hungarian notation
Never give a table the same name as one of its columns
Avoid, where possible, concatenating two table names together to create the name of a relationship table. Rather than car_mechanic prefer service

{% highlight sql %}{% include sql/naming_conventions.sql %}{% endhighlight %}

Columns

Always use the singular name
Avoid simply using id as the primary identifier for the table
Do not add a column with the same name as its table
Always use lowercase except where it may make sense not to such as proper nouns

{% highlight sql %}{% include sql/naming_conventions.sql %}{% endhighlight %}

Aliasing or correlations

Should relate in some way to the object or expression they are aliasing
As rule of thumb the correlation name should be the first letter of each word in the object's name
If there is already a correlation with same name then append a number
Always include the AS keyword—makes it easier to read as it is explicit
For computed data (SUM() or AVG()) use the name you would give it were it a column defined in the schema

{% highlight sql %}{% include sql/naming_correlations.sql %}{% endhighlight %}

Stored procedures

The name must contain a verb
Do not prefix with sp_ or any other such descriptive prefix or Hungarian notation

{% highlight sql %}{% include sql/naming_conventions.sql %}{% endhighlight %}

Uniform postfixes

_id—a unique identifier such as a column that is a primary key
_status—flag value or some other status of any type such as publication_status
_total—the total or sum of a collection of values
_name—signifies a name such as first_name
_seq—contains a contiguous sequence of values
_date—denotes a column that contains the date of something
_tally—a count
_size—the size of something such as a file size or clothing
_addr—an address for the record could be physical or intangible such as ip_addr

{% highlight sql %}{% include sql/naming_conventions.sql %}{% endhighlight %}

Overview

General

Avoid the use of

Syntax

Reserved words

Indentation

White space

Naming conventions

General

Tables

Columns

Aliasing or correlations

Stored procedures

Uniform postfixes

Appendices

Reserved keyword reference