Here’s a detailed comparison between ENUM and SET in MySQL:
| Feature | ENUM | SET |
|---|---|---|
| Definition | A string object that can have only one value chosen from a list of predefined values. | A string object that can have multiple values, each chosen from a predefined list. |
| Number of Values | Only one value from the list can be stored. | Can store zero or more values from the list. |
| Storage | Stores internally as 1 or 2 bytes depending on the number of possible values. | Stores internally as bitmap (up to 8 bytes) for multiple selections. |
| Syntax | ENUM('value1', 'value2', 'value3') | SET('value1', 'value2', 'value3', ...) |
| Use Case | When you want to restrict a column to one choice among many predefined options. | When you want to allow a column to have multiple choices simultaneously. |
| Example | sql CREATE TABLE users (status ENUM('active', 'inactive', 'pending')); | sql CREATE TABLE products (colors SET('red', 'green', 'blue')); |
| Insertion | Only one value allowed: INSERT INTO users (status) VALUES('active'); | Multiple values allowed: INSERT INTO products (colors) VALUES('red,blue'); |
| Querying | Check for exact match: WHERE status='active' | Check for a value using FIND_IN_SET or bit operations: WHERE FIND_IN_SET('red', colors) |
| Advantages | Lightweight, easy validation, ensures only one valid value. | Flexible, allows multiple selections, still compact storage. |
| Limitations | Only one value; cannot select multiple options. | Limited to 64 members; querying multiple values can be less intuitive. |
Summary:
- ENUM: Single choice from a list.
- SET: Multiple choices from a list.