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(hào)是___C___。

　　A、“+” B、“&” C、“||” D、“|”