>
> Hello list,
>
> is there a common naming system for db objects ?
Thousands.
> Like:
>
> 1) Tables: mytable, tblmytable, tbl_mytable
>
> 2) Indices: idx_anindex
>
> 3) Columns: int_somenumber, date_lastupdate
>
> 4) id for the numerical primary key e.g. table customers.id
> and then for referencing foreign keys
> table addresses : addresses.customer_id or
> addresses.customer_fk
>
> OK, I know I could name them the way I want but perhaps there is some
> kind of common sense in this regard ?
Common sense will do, but here is my take on it.
There are three main objectives - portability, maintainability and
consistency.
General.
Use long names. Don't abbreviate unnecessarily, but don't go to far that
you have
to rename all your tables if you move to a different DBMS. A max of 30
chars should fit most DBMSs.
Use lower case names, with words separated by underscores '_'. Some DBMSs
are case
sensitive, others aren't and some convert all names to upper case ( this is
an ANSI
standard feature, I believe). If you use camel case ( studentClassScores),
this could become
STUDENTCLASSSCORES which isn't very readable, whereas STUDENT_CLASS_SCORES
is much better.
Don't use reserved words. Most DBMSs allow you to use reserved words with
various degrees of effort, but why bother. Also try to avoid simple names
which
might be a reserved word in another DBMS.
Tables.
Give tables a clear simple name which represents the content. If it holds
student records, call
it "students"; course details, "courses" etc.
Also assign each table a unique 2-4 letter prefix for use in naming objects
which belong to that table.
Columns
Again say what it is. I use the prefix referred to above in all column
names, but some people think that
is a waste of name space.
e.g std_id, std_surname, std_forename, student_birthdate, crs_name,
crs_tutor_id, etc
Constraints
Use the prefix
Primary Key std_pk
Foreign Keys std_fk_col ( i.e. <source_prefix>_FK_<target_prefix>
Unique Keys std_uk_nn where nn is a sequence number. Some people like
std_uk_<column_name>, but
if you have a composite key, that doesn't
work.
Indexes
Where an index is used to enforce (or instead of) a unique or primary key
constraint, same name as the constraint.
Primary Key index std_pk
Unique Index std_uk_nn
Non-unique index std_nu_nn
If indexes share the same namespace as constraints, stick an i_ on the
front of the index name.
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