This is an example for the page about sheaves which is here.
Example - Relational Database
This could be a generalisation of the sheaf concept.
Here Cop is a database schema.
This imposes a structure on the sets which are the database tables.
See simplical databases.
Relational databases link tables by having shared keys.
This gives a structure to the table which must play well with the structure of the schema.
As an example here are some key values.
In this case a mapping from T1 to T2 is injective which corresponds to T2 being a subset of T1.
Relational databases have many to one relationships between tables. For instance part of census data may have
There might then be a many to one relationship between these two tables.
More information about relational databases on page here.
|In order to implement many to many relationships between tables we need to insert an extra table between them: