Constraint naming standard

By Michael Bryzek

+Constraint naming standard

Prev	Chapter�12.�Engineering Standards	Next

Constraint naming standard

By Michael Bryzek

OpenACS docs are written by the named authors, and may be edited by OpenACS documentation staff. -

The Big Picture

Constraint naming standard is important for one reason: The SYS_* name oracle assigns to unnamed constraints is not very understandable. By correctly naming all contraints, we can quickly associate a particular constraint @@ -10,14 +10,14 @@

Why do we need a naming convention?

Oracle limits names, in general, to 30 characters, which is hardly enough for a human readable constraint name. -

Abbreviations

We propose the following naming convention for all constraints, with the following abbreviations taken from Oracle Docs at http://oradoc.photo.net/ora81/DOC/server.815/a67779/ch4e.htm#8953. Note that we shortened all of the constraint abbrevations to two characters to save room. -

Constraint type	Abbreviation
references (foreign key)	fk
unique	un
primary key	pk
check	ck
not null	nn

Format of constraint name

Constraint type	Abbreviation
references (foreign key)	fk
unique	un
primary key	pk
check	ck
not null	nn

Format of constraint name

In reality, this won't be possible because of the character limitation on @@ -27,7 +27,7 @@

Truncate the column name until it fits.

If the constraint name is still too long, you should consider rewriting your entire data model :) -

Notes:

If you have to abbreviate the table name for one of the constraints, abbreviate it for all the constraints
If you are defining a multi column constraint, try to truncate the two column names evenly

Example

Notes:

If you have to abbreviate the table name for one of the constraints, abbreviate it for all the constraints
If you are defining a multi column constraint, try to truncate the two column names evenly

Example

 create table example_topics (
        topic_id    integer
 		   constraint example_topics_topic_id_pk
@@ -51,7 +51,7 @@
        constraint cne_example_id_one_line_unq unique(example_id, one_line_description)
 );
 
-

Why it's good to name primary keys

Naming primary keys might not have any obvious advantages. However, here's an example where naming the primary key really helps (and this is by no means a rare case! @@ -72,7 +72,7 @@

Isn't it nice to see "EXAMPLE_TOPICS_TOPIC_ID_PK" in the trace and know exactly which table oracle is using at each step? -

Naming not null constraints is optional...

People disagree on whether or not we should be naming not null constraints. So, if you want to name them, please do so and follow the above naming standard. But, naming not null constraints is not a