要在表CUSTOMERS的字段CUST_FIRST_NAME建个约束，使这个字段不能包含数字。您将使用哪个SQL语句来完成任务?a A. ALTER TABLE CUSTOMERS ADD CONSTRAINT cust_f_name CHECK(REGEXP_LIKE(cust_first_name,'[^0-9]')) NOVALIDATE; B. ALTER TABLE CUSTOMERS ADD CONSTRAINT cust_f_name CHECK(REGEXP_LIKE(cust_first_name,'[[:digit:]]')) NOVALIDATE; C. ALTER TABLE CUSTOMERS ADD CONSTRAINT cust_f_name CHECK(REGEXP_LIKE(cust_first_name,'[[:alpha:]]')) NOVALIDATE; D. ALTER TABLE CUSTOMERS ADD CONSTRAINT cust_f_name CHECK(REGEXP_LIKE(cust_first_name,'^AZ')) NOVALIDATE;