(
EMP_ID NUMBER(4) NOT NULL
LAST_NAME VARCHAR2(30) NOT NULL
FIRST_NAME VARCHAR2(30)
DEPT_ID NUMBER(2)
JOB_CAT VARCHAR2(30)
SALARY NUMBER(8,2)
)
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;
b.
这行文字是为了凑十个字符
each job category of each department，显示就是按department，category分组。maximum salary 就是max(salary)。所以选b
选B
我也要凑是个字符么？
正确答案：B
max为聚合函数，需要按照什么分组来做聚合，所以需要把查询的其他项在group by中写出来。
这行文字是为了凑十个字符