How to convert month number to month strings with PostgreSQL conditionals

query.sql

SELECT *,
CASE WHEN month = 1 THEN 'January'
WHEN month = 1 THEN 'January'
WHEN month = 2 THEN 'February'
WHEN month = 3 THEN 'March'
WHEN month = 4 THEN 'April'
WHEN month = 5 THEN 'May'
WHEN month = 6 THEN 'June'
WHEN month = 7 THEN 'July'
WHEN month = 8 THEN 'August'
WHEN month = 9 THEN 'September'
WHEN month = 10 THEN 'October'
WHEN month = 11 THEN 'November'
ELSE 'December' END as month_string
FROM table_name