Final answer:
The asset ID number serving as a unique identifier for the fixed asset ledger is considered to be the primary key. A primary key uniquely defines each record in a database table and cannot have null values. It is distinct from a foreign key, which links two tables, and a unique key, which also ensures data uniqueness but can contain null values.
Step-by-step explanation:
If the asset ID number is a unique identifier for the fixed asset ledger, it would be considered to be the primary key. In database management, a primary key is a specific choice of a minimal set of attributes (columns) that uniquely define a tuple (row) in a relation (table). The primary key’s main features are that it must contain a unique value for each row of data, and it cannot contain null values.
A foreign key, on the other hand, is a set of one or more columns in a table that refers to the primary key in another table. The foreign key establishes a link between the data in two tables to control the data that can be stored in the foreign key table. Meanwhile, a unique key is a constraint that also ensures data uniqueness within the database table but can contain a null value. Primary keys and unique keys ensure the integrity of the data in the database by preventing duplicate records.