多项选择题
A. SELECT TOTAL(*) FROM customers;
B. SELECT COUNT(*) FROM customers;
C. SELECT TOTAL(customer_id) FROM customers;
D. SELECT COUNT(customer_id) FROM customers;
E. SELECT COUNT(customers) FROM customers;
F. SELECT TOTAL(customer_name) FROM customers;
单项选择题 Examine the description of the EMPLOYEES table: EMP_ID NUMBER(4) NOT NULL LAST_NAME VARCHAR2(30) NOT NULL FIRST_NAME VARCHAR2(30) DEPT_ID NUMBER(2) Which statement produces the number of different departments that have employees with last name Smith?（）
单项选择题 Which is an iSQL*Plus command?（）
单项选择题 Which SQL statement would you use to remove a view called EMP_DEPT_VU from your schema?（）
