CHECK CONSTRAINT of string to contain only digits. (Oracle SQL)

Question

I have a column, say PROD_NUM that contains a 'number' that is left padded with zeros. For example 001004569. They are all nine characters long.

I do not use a numeric type because the normal operation on numbers do not make sense on these "numbers" (For example PROD_NUM * 2 does not make any sense.) And since they are all the same length, the column is defined as a CHAR(9)

CREATE TABLE PRODUCT (
    PROD_NUM CHAR(9) NOT NULL
    -- ETC.
)

I would like to constrain PROD_NUM so it can only contain nine digits. No spaces, no other characters besides '0' through '9'

Answer 1

REGEXP_LIKE(PROD_NUM, '^[[:digit:]]{9}$')