单项选择题
A. There is no row with dept_id 90 in the EMPLOYEES table.
B. You cannot delete the JOB_ID column because it is a NOT NULL column.
C. You cannot specify column names in the DELETE clause of the DELETE statement.
D. You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.
单项选择题 Which substitution variable would you use if you want to reuse the variable without prompting the user each time?（）
单项选择题 What is true about the WITH GRANT OPTION clause?（）
单项选择题 The EMP table has these columns: Management wants a list of names of employees who have been with the company for more than five years. Which SQL statement displays the required results?（）
