validate a numeric column postgres

im trying to validate a column using postgresql
where values in the column are (0000-ASZAS) four numerical values-five alphbets

SELECT invoice_number,
CASE
WHEN invoice_number = '[0-9][0-9][0-9][0-9]-[A-Z][A-Z][A-Z][A-Z][A-Z]' 
THEN 'valid'
ELSE 'invalid'
END
from invoices;

also tried LIKE instead of =

>Solution :

You may use the ~ POSIX regex operator:

SELECT invoice_number,
       CASE WHEN invoice_number ~ '^[0-9]{4}-[A-Z]{5}$' 
            THEN 'valid'
            ELSE 'invalid' END
FROM invoices;