A. Both tables have NULL values.B. You want all unmatch……

多项选择题Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Which three statements inserts a row into the table? （）

A. INSERT INTO employees VALUES (NULL, 'JOHN','Smith');
B. INSERT INTO employees( first_name, last_name) VALUES ('JOHN','Smith');
C. INSERT INTO employees VALUES ('1000','JOHN','NULL');
D. INSERT INTO employees(first_name,last_name, employee_id) VALUES ('1000, 'john','Smith');
E. INSERT INTO employees (employee_id) VALUES (1000);
F. INSERT INTO employees (employee_id, first_name, last_name) VALUES ( 1000, 'john',");

单项选择题Evaluate the SQL statement: SELECT LPAD (salary,10,*) FROM EMP WHERE EMP _ ID = 1001; If the employee with the EMP_ID 1001 has a salary of 17000, what is displayed?（）

A. 17000.00
B. 17000*****
C. ****170.00
D. **17000.00
E. an error statement

单项选择题Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables: EMPLOYEES EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE NEW_EMPLOYEES EMPLOYEE_ID NUMBER Primary Key NAME VARCHAR2 (60) Which DELETE statement is valid?（）

A. DELETE FROM employees WHERE employee_id = (SELECT employee_id FROM employees);
B. DELETE * FROM employees WHERE employee_id = (SELECT employee_id FROM new_ employees);
C. DELETE FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = 'carrey');
D. DELETE * FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = 'carrey');

多项选择题Evaluate this SQL statement: SELECT e.emp_name, d.dept_name FROM employees e JOIN departments d USING (department_id) WHERE d.department_id NOT IN (10,40) ORSER BY dept_name; The statement fails when executed. Which change fixes the error?（）

A. remove the ORDER BY clause
B. remove the table alias prefix from the WHERE clause
C. remove the table alias from the SELECT clause
D. prefix the column in the USING clause with the table alias
E. prefix the column in the ORDER BY clause with the table alias
F. replace the condition "d.department_id NOT IN (10,40)" in the WHERE clause with "d.department_id <> 10 AND d.department_id <> 40"

多项选择题Which three statements about subqueries are true? （）

A. A main query can have more than one subquery.
B. A subquery can have more than one main query.
C. The subquery and main query must retrieve data from the same table.
D. The subquery and main query can retrieve data from different tables.
E. Only one column or expression can be compared between the subquery and main query.
F. Multiple columns or expression can be compared between the subquery and main query.