单项选择题
A. SELECT employee_id, salary, tax_percent FROM employees e, tax t WHERE e.salary BETWEEN t.min_salary AND t.max_salary;
B. SELECT employee_id, salary, tax_percent FROM employees e, tax t WHERE e.salary > t.min_salary, tax_percent
C. SELECT employee_id, salary, tax_percent FROM employees e, tax t WHERE MIN(e.salary) = t.min_salary AND MAX(e.salary) = t.max_salary
D. You cannot find the information because there is no common column between the two tables.
单项选择题 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?（）
单项选择题 You are the DBA for an academic database. You need to create a role that allows a group of users to modify existing rows in the STUDENT_GRADES table.Which set of statements accomplishes this?（）
单项选择题 Evaluate this SQL statement: SELECT ename, sal, 12* sal+100 FROM emp; The SAL column stores the monthly salary of the employee. Which change must be made to the above syntax to calculate the annual compensation as "monthly salary plus a monthly bonus of $100, multiplied by 12"?（）
