Acesse o desafio: http://novidades.aprendaplsql.com/15-dias-de-funcoes-oracle
A Função TO_CHAR é uma função que transforma o parâmetro do tipo DATE ou NUMBER em um parâmetro do tipo CHAR.
SELECT to_char(hire_date, 'YYYYMMDD') AS "TO_CHAR"
FROM hr.employees;
SELECT to_char(1210.73, '9999.9') AS "TO_CHAR"
FROM dual;
SELECT to_char(-1210.73, '9999.9') AS TO_CHAR
FROM dual;
SELECT to_char(1210.73, '9,999.99') AS TO_CHAR
FROM dual;
SELECT to_char(1210.73, '$9,999.00') AS TO_CHAR
FROM dual;
SELECT to_char(21, '000099') AS TO_CHAR
FROM dual;
SELECT to_char(21, '99999') AS TO_CHAR
FROM dual;
Funções Oracle SQL
https://www.youtube.com/watch?v=PjaBYIwXf8c&list=PLMaqczuL07LkjrX6Rvx6TdNM-1nbUKG8p
