Introduction:

In this blog, we will learn the multiple methods for converting strings to ENUM in MySQL, complete with code examples, program outputs, and comprehensive explanations.

Method 1: Using ALTER TABLE Statement

The ALTER TABLE statement is a powerful tool for modifying table structures in MySQL. Here's a step-by-step guide on converting a string column to ENUM using this method:

Backup Your Data:

Before making any changes, ensure you have a backup of your data to prevent potential data loss.

Alter the Column:

Use ALTER TABLE with the MODIFY clause to change the data type of the column from VARCHAR to ENUM. Specify the ENUM values within single quotes.

ALTER TABLE employees
MODIFY department ENUM('IT', 'HR', 'Finance');

Update Existing Data:

If your column contains existing data, update it to match the ENUM values.

UPDATE employees
SET department = 'IT'
WHERE department = 'Information Technology';

Output:

Query OK, 5 rows affected (0.03 sec)
Rows matched: 5  Changed: 5  Warnings: 0

Method 2: Using Temporary Columns

This method involves creating a temporary column, populating it with ENUM-converted values, and finally dropping the original column. This approach is helpful when you need to retain the original data.

Add Temporary Column:

Add a new temporary ENUM column to the table.

ALTER TABLE employees
ADD temp_department ENUM('IT', 'HR', 'Finance');

Update Temporary Column:

Update the temporary column with the converted ENUM values.

UPDATE employees
SET temp_department = 'HR'
WHERE department = 'Human Resources';

Drop Original Column and Rename:

Drop the original string column and rename the temporary column.

ALTER TABLE employees
DROP COLUMN department,
CHANGE temp_department department ENUM('IT', 'HR', 'Finance');

Output:

Query OK, 5 rows affected (0.02 sec)
Records: 5  Duplicates: 0  Warnings: 0

Method 3: Using CASE Statements

CASE statements offer a versatile way to update column values based on conditions, making it perfect for converting strings to ENUM values.

Update Column Using CASE Statement:

Utilize the CASE statement to update the column values.

UPDATE employees
SET department = CASE
    WHEN department = 'IT Department' THEN 'IT'
    WHEN department = 'Human Resources' THEN 'HR'
    ELSE department
END;

Output:

Query OK, 5 rows affected (0.03 sec)
Rows matched: 5  Changed: 5  Warnings: 0

Conclusion:

In this blog, we have explored three distinct methods to convert strings to ENUM in MySQL: using the ALTER TABLE statement, temporary columns, and CASE statements.