選擇題：

1)Which statement shows the maximum salary paid in each job category of each department?_______

A、 select dept_id， job_cat，max(salary) from employees where salary > max(salary);

B、 select dept_id， job_cat，max(salary) from employees group by dept_id，job_cat;

C、 select dept_id， job_cat，max(salary) from employees;

D、 select dept_id， job_cat，max(salary) from employees group by dept_id;

E、 select dept_id， job_cat，max(salary) from employees group by dept_id，job_cat，salary;

2)description of the students table:

sid_id number

start_date date

end_date date

which two function are valid on the start_date column?_________。

A、 sum(start_date)

B、 avg(start_date)

C、 count(start_date)

D、 avg(start_date，end_date)

E、 min(start_date)

F、 maximum(start_date)

3)for which two constraints does the oracle server implicitly create a unique index?______。

A、 not null

B、 primary

C、 foreign key

D、 check

E、 unique

4)in a select statement that includes a where clause，where is the group by clause placed in the select statement?______。

A、 immediately after the select clause

B、 before the where clause

C、 before the from clause

D、 after the order by clause

E、 after the where clause

5)in a select statement that includes a where clause，where is the order by clause placed in the select statement?______。

A、immediately after the select clause

B、before the where clause

C、after all clause

D、after the where clause

E、before the from clause

6)evaluate there two sql statements______。

Select last_name，salary from employees order by salary;

Select last_name，salary from employees order by 2 asc;

A。the same result B。different result C。the second statement returns a syntax error

7) you would like to display the system date in the format“20051110 14：44：17”。Which select statement should you use?______。

A、 select to_date(sydate，’yearmmdd hh:mm:ss’)from dual;

B、select to_char(sydate，’yearmonthday hh:mi:ss’)from dual;

C、select to_date(sydate，’yyyymmdd hh24:mi:ss’)from dual;

D、 select to_char(sydate，’yyyymmdd hh24:mi:ss’)from dual;

E、select to_char(sydate，’yy-mm-dd hh24:mi:ss’)from dual;

8)which select statement will the result ‘ello world’from the string‘Hello world’?______。

A、select substr(‘Hello World’，1)from dual;

B、select substr(trim(‘Hello World’，1，1))from dual;

C、select lower(substr(‘Hello World’，1))from dual;

D、select lower(trim(‘H’from‘Hello World’))from dual;

9)which are DML statements(choose all that apply)______。

A、mit B、merge C、update D、delete E、creat F、drop

10)Select 語句中用來連接字符串的符號是___C___。

A、“+” B、 “&” C、“||” D、“|”