单选题Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?（）AALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;BALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;CALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn NOT NULL;DALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn IS NOT NULL;EALTER TABLE customers MODIFY name CONSTRAINT cust_name_nn NOT NULL;FALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name NOT NULL;
单选题
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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单选题You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty. Which statement accomplishes this task?（）AALTER TABLE students ADD PRIMARY KEY _ id;BALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);CALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;DALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);EALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id);
多选题You need to design the restrictions on the Bank.Customers table. Which three actions should you perform?（）ADesign a trigger that verifies that the first names and surnames are not empty strings.BDesign a check constraint that verifies that the first names and surnames are not empty strings.CDesign a check constraint that uses a CLR user-defined function to verify that either the phone number is a null value or the format of the phone number is valid.DDesign a trigger that uses a CLR user-defined function to verify that either the phone number is a null value or the format of the phone number is valid.EDesign a check constraint that ensures that the phone number cannot be changed from a valid format to a null value or to an invalid format.FDesign a trigger that ensures that the phone number cannot be changed from a valid format to a null value.
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单选题You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty.Which statement accomplishes this task?（）AALTER TABLE students ADD PRIMARY KEY student_id;BALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student _ id);CALTER TABLE students ADD CONSTRAINT stud _ id _pk PRIMARY KEY (student _ id);DALTER TABLE students MODIFY CONSTRAINT stud _ id _pk PRIMARY KEY (student _ id);
单选题You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty. Which statement accomplishes this task?（）AALTER TABLE students ADD PRIMARY KEY student_id;BALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);CALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;DALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);EALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id);
多选题Examine the following statement that is used to modify the constraint on the SALES table： SQL ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE； Which three statements are true regarding the above command（）AThe constraint remains valid.BThe index on the constraint is dropped.CIt allows the loading of data into the table using SQL*Loader.DNew data conforms to the constraint， but existing data is not checkedEIt allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.
单选题What type of constraint is used to ensure that each row inserted into the EMPLOYEE table with a value in the WORKDEPT column has a row with a corresponding value in the DEPTNO column of the DEPARTMENT table?（）AA check constraint on the EMPLOYEE tableBA unique constraint on the EMPLOYEE table WORKDEPT columnCA foreign key reference from the DEPARTMENT tables DEPTNO column to the WORKDEPT column of the EMPLOYEE tableDA foreign key reference from the EMPLOYEE tables WORKDEPT column to the DEPTNO column of the DEPARTMENT table
单选题Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?（）AALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;BALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;CALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn NOT NULL;DALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn IS NOT NULL;EALTER TABLE customers MODIFY name CONSTRAINT cust_name_nn NOT NULL;FALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name NOT NULL;