单项选择题
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;
相关考题
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多项选择题
Which two statements are true regarding the ORDER BY clause?（）
A. The sort is in ascending by order by default.
B. The sort is in descending order by default.
C. The ORDER BY clause must precede the WHERE clause.
D. The ORDER BY clause is executed on the client side.
E. The ORDER BY clause comes last in the SELECT statement.
F. The ORDER BY clause is executed first in the query execution. -
多项选择题
Which two tasks can your perform by using the TO_CHAR function?（）
A. Convert 10 to ‘TEN’
B. Convert ‘10’ to 10
C. Convert ‘10’ to ‘10’
D. Convert ‘TEN’ to 10
E. Convert a date to a character expression
F. Convert a character expression to a date -
多项选择题
Top N analysis requires （） and （）.
A. the use of rowid
B. a GROUP BY clause
C. an ORDER BY clause
D. only an inline view
E. an inline view and an outer query
