Question

Suppose I have two tables in a parent – child relationship. Let’s call them “sites” and “buildings” where a “site” is a parent of one or more “buildings”. I want the IDs to be unique across databases so I will be using GUIDs for the IDs.

Should I prefer generic names for the ID fields in the tables or strongly typed names and why?

Example 1 (Generic Names):

CREATE TABLE sites (
   id VARCHAR(38) NOT NULL,
   -- other attributes
);

CREATE TABLE buildings (
   id VARCHAR(38) NOT NULL,
   parent_id VARCHAR(38) NOT NULL,
   -- other attributes
);

Example 2 (Strongly Typed Names):

CREATE TABLE sites (
   site_guid VARCHAR(38) NOT NULL,
   -- other attributes
);

CREATE TABLE buildings (
   building_guid VARCHAR(38) NOT NULL,
   site_guid VARCHAR(38) NOT NULL,
   -- other attributes
);

Answer 1

I prefer to use building_id, site_id so that the column name defines its contents more explicitly than just “id”. This also makes it possible to use the ANSI join “using” syntax:

select site.site_id, building.building_id
from building
join site using (site_id);

Another advantage is that when such columns are used in queries (or views or subqueries), they don’t need re-aliasing so often – like this:

select site.id as site_id, building.id as building_id
from building
join site on site.id = building.site_id;