多项选择题
A. SELECT TOTAL(*) FROM customer;
B. SELECT COUNT(*) FROM customer;
C. SELECT TOTAL(customer_id) FROM customer;
D. SELECT COUNT(customer_id) FROM customer;
E. SELECT COUNT(customers) FROM customer;
F. SELECT TOTAL(customer_name) FROM customer;
多项选择题 Which four statements correctly describe functions that are available in SQL? （）
单项选择题 You need to create a view EMP_VU. The view should allow the users to manipulate the records of only the employees that are working for departments 10 or 20. Which SQL statement would you use to create the view EMP_VU? （）
多项选择题 From SQL*Plus, you issue this SELECT statement: SELECT* FROM order; You use this statement to retrieve data from a data table for （）.