A different database keys

A side-by-side comparison of the different database keys

Short Descriptions:

1. Table 1: Provides an overview of the different types of database keys, their primary descriptions, and their main characteristics and usages.

2. Table 2: Lists the advantages (pros) and disadvantages (cons) of each key type, helping in understanding when and why to use each key.

Table 1: Database Keys Overview

Key Type	Description	Characteristics & Usage
Primary Key	Unique identifier for a record in a table.	- Uniqueness guaranteed. - Often numeric & auto-incremented. - Used to establish relationships.
Foreign Key	Refers to the primary key of another table.	- Maintains referential integrity. - Defines relationships between tables.
Composite Key	Key that consists of two or more columns to ensure uniqueness.	- Used when no single data element uniquely identifies instances.
Candidate Key	Column(s) that can qualify as a unique key.	- Each candidate key is unique and non-null. - One is chosen as the primary key.
Surrogate Key	Artificial key uniquely generated by the database system.	- Database-generated. - Used as primary key when natural key is unsuitable.
Natural Key	Unique key composed of columns that exist naturally in the data.	- Derived from application data. - Used when there's a clear, reliable, and immutable candidate for PK.

Table 2: Pros and Cons of Key Types

Key Type	Pros	Cons
Primary Key	- Ensures record uniqueness. - Speeds up data retrieval.	- Choosing the wrong primary key can lead to performance issues.
Foreign Key	- Ensures referential integrity. - Enables logical relationships between tables.	- Can complicate data insertion due to dependencies.
Composite Key	- Allows for unique combinations of multiple columns. - Useful for representing relationships.	- Can become complex. - Might lead to slower query performance.
Candidate Key	- Provides options for primary key selection. - Ensures uniqueness.	- Having too many can complicate database design.
Surrogate Key	- Always unique. - Not tied to business logic, so less likely to change.	- Doesn't have a natural or business meaning. - Can lead to "meaningless" primary keys.
Natural Key	- Meaningful and can be used in business logic. - Can simplify queries.	- Can change over time, complicating updates. - Might not always be unique or might become complex.

I hope these tables provide a clearer, side-by-side understanding of the different database keys. If you have any further questions or need more details, please let me know!