【单选题】Examine the description of the EMPLOYEES table: Which statement produces the number of different departments that have employees with last name Smith?()
A.
SELECT COUNT(*) FROM employees WHERE last_name='Smith';
B.
SELECT COUNT(dept_id) FROM employees WHERE last_name='Smith';
C.
SELECT DISTINCT(COUNT(dept_id)) FROM employees WHERE last_name='Smith';
D.
SELECT COUNT(DISTINCT dept_id) FROM employees WHERE last_name='Smith';
E.
SELECT UNIQUE(dept_id) FROM employees WHERE last_name='Smith';
【单选题】EMPLOYEES表包含以下字段: FIRST-NAME VARCHAR2(25) COMMISSION NUMBER(3) 执行 SELECT FIRST-NAME, COMMISSION FROM EMPLOYEESS WHERE COMMISSION =(SELECT COMMISSION FROM EMPLOYEES WHERE UPPER(FIRST-NAME)=‘SCOTT’) 什么条...
A.
Scott has a null commission resolution
B.
Scott has a zero commission resolution
C.
There is not a employees with the first name Scott
D.
The first name values in the date base are in the lower case