Understanding the Types of Keys in DBMS: A Comprehensive Guide
Exploring the Role and Varieties of Keys in Database Management
The Essence of Keys in DBMS
Keys in DBMS are crucial for data integrity, efficient retrieval, and consistency. Let’s explore the different types.
| Type of Key | Description |
|---|---|
| Candidate Key | Potential unique identifiers for each entity; e.g., ID, name, mobile number. |
| Primary Key | A unique key for every entity; often an ID number. |
| Alternate Key | Other candidate keys after selecting the primary key. |
| Foreign Key | Links tables together; a primary key is used in another table. |
| Composite Key | Combination of two or more keys to create a unique identifier. |
| Super Key | A combination of keys to ensure unique identification. |
| Unique Key | Can contain NULL values; a mix of alternate keys. |
Understanding NULL Values in DBMS
NULL values indicate the absence of a value, crucial for data integrity. It’s different from an empty string or zero.
