Databases: Primary, Foreign and Alternate Keys
This introduces some terminology frequently used in relations databases.
In a database table, certain columns are keys. Keys help identify rows
/ records and link records together.
Primary Key
Uniquely identifies a record/row/object/person.
Alternate Key
Also uniquely identifies a record/row/object/person
Foreign Key
Related tables are linked together by taking the primary key from one
table and placing in the related table. The primary key then becomes a
foreign key.
In this case, if we had another table that described Institutions’,
then the Institution column in the Instructors table would be a
foreign key.
Example
The Instructors table, again.
Instructor Table
| Scott Cain |
Ontario Institute for Cancer Research |
scott@scottcain.net |
| Tim Carver |
Sanger Institute |
tjc@sanger.ac.uk |
| Dave Clements |
NESCent |
clements@nescent.org |
| Stephen Ficklin |
Clemson University |
ficklin@clemson.edu |
| Syed Haider |
EBI |
syed@ebi.ac.uk |
| Ian Holmes |
UC Berkeley |
ihh@berkeley.edu |
| Carson Holt |
University of Utah |
carson.holt@utah.ed |
| Robin Houston |
Sanger Institute |
rh11@sanger.ac.uk |
| Ed Lee |
Lawrence Berkeley National Lab |
elee@berkeleybop.org |
| Sheldon McKay |
Cold Spring Harbor Laboratory |
mckays@cshl.edu |
| Joshua Orvis |
Institute for Genome Sciences |
jorvis@som.umaryland.edu |
| Mitch Skinner |
UC Berkeley |
mitch_skinner@berkeley.edu |
| Giles Velarde |
Wellcome Trust Sanger Institute |
gv1@sanger.ac.uk |
| Junjun Zhang |
Ontario Institute for Cancer Research |
Junjun.Zhang@oicr.on.ca |
|
Note
This simplified table contains a number of bad practices, such as the
primary and foreign key values used, and naming conventions. We’ll get
to those.
Back to Chado Tutorial.
Navigation
Documentation