MySQL ENUM

The MySQL ENUM data type is used to store a list of predefined values within a column. An ENUM column can store one of the enumerated values, which are defined during the table creation. This is useful when you have a specific set of values that a column can take, and you want to enforce data integrity by allowing only those values.

The basic syntax for creating an ENUM column in a MySQL table is as follows:

column_name ENUM('value1', 'value2', ..., 'valueN')

• column_name: The name of the column.
• 'value1', 'value2', ..., 'valueN': The list of allowed values for the column.

Here’s an example of how to create a table with an ENUM column:

CREATE TABLE colors (
    color_id INT,
    color_name ENUM('Red', 'Green', 'Blue', 'Yellow')
);

In this example, the color_name column is defined as an ENUM that can only store one of the four specified values: ‘Red’, ‘Green’, ‘Blue’, or ‘Yellow’.

To insert data into an ENUM column, you need to use one of the predefined values:

INSERT INTO colors (color_id, color_name) VALUES (1, 'Red');

You can also query data using the ENUM values:

SELECT * FROM colors WHERE color_name = 'Green';

Keep in mind the following when working with ENUM:

1. The values stored in an ENUM column are case-insensitive. ‘Red’ and ‘red’ are treated as the same value.
2. You cannot add new values to an existing ENUM definition easily. If you need to modify the allowed values, it may require altering the table structure.
3. While ENUM can enforce data integrity, it may not be as flexible as other data types like VARCHAR for storing text data with variable values.
4. When using ENUM, it’s essential to carefully choose the set of values to avoid data inconsistencies.

ENUM can be useful for columns with a limited set of possible values, such as status indicators, categories, or types, where you want to ensure that only predefined values are allowed in the column.