Which statement adds a constraint that ensures the CUST…

Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table
holds a value?

Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table
holds a value?

A.
ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;

B.
ALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;

C.
ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn NOT NULL;

D.
ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn IS NOT NULL;

E.
ALTER TABLE customers MODIFY name CONSTRAINT cust_name_nn NOT NULL;

F.
ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name NOT NULL;



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the tuk

the tuk

SQL> conn tanawat/welcome1
Connected.

SQL> desc employees
Name Null? Type
—————————————– ——– —————————-
EMPLOYEE_ID NUMBER
LOGIN_ID NUMBER
EMPLOYEE_NAME VARCHAR2(100)
HIRE_DATE DATE

SQL>
SQL> alter table employees modify employee_name constraint emp_name_nn NOT NULL ;

Table altered.

SQL> desc employees
Name Null? Type
—————————————– ——– —————————-
EMPLOYEE_ID NUMBER
LOGIN_ID NUMBER
EMPLOYEE_NAME NOT NULL VARCHAR2(100)
HIRE_DATE DATE

SQL>

Robin

Robin

A is wrong just because it’s missing parenthesis in the expression “customer_name IS NOT NULL”.