【单选题】
（）name is Wanghua.
A、He
B、He’s
C、His
查看正确答案
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;
