Data Modeling - Identifier - (Id|Primary|Natural|Surrogate|Business) key
Table of Contents
1 - About
A group of attributes that uniquely identifies an instance of an entity is called a concatenated key.
A primary key is that candidate key which will most commonly be used to uniquely identify a single entity instance.
Any candidate key that is not selected to become the primary key is called an alternate key.
Same concept, see also: Security - Identity (id of an entity)
2 - Articles Related
3 - Example
4 - Identifier
An identifier data type must be able to hold any key value.
A common implementation of this data type will be an integer. However, the column values can exceed the range of integer values supported by a 4-byte integer and other data type such as as 8-byte integer, decimal or character string may be needed.
5 - Keys
5.1 - Primary
5.2 - Surrogate
5.3 - Natural
If the table has a true primary key – it is known as a “natural key”