62、(13-17)choose the best answer:

You need to list the employees in DEPARTMENT_ID 30 in a single row, ordered by HIRE_DATE.

Examine the sample output:

Which query will provide the required output?

A) SELECT LISTAGG(last_name, '; ') "Emp_list", MIN(hire_date) "Earliest"

FROM employees

WHERE department_id = 30

WITHIN GROUP ORDER BY hire_date;

B) SELECT LISTAGG(last_name, '; ') "EMP_LIST", MIN(hire_date) "Earliest"

FROM employees

WHERE department_id = 30

ORDER BY hire_date;

C) SELECT LISTAGG(last_name, '; ')

WITHIN GROUP (ORDER BY hire_date) "Emp_list", MIN(hire_date) "Earliest"

FROM employees

WHERE department_id = 30;

D) SELECT LISTAGG(last_name)

WITHIN GROUP ORDER BY (hire_date) "Emp_list", MIN(hire_date) "Earliest"

FROM employees

WHERE department_id = 30;

Answer:C

(解析：工作中会用到把查出来的列的值去重合并成一行显示，可以使用 listagg() WITHIN GROUP () 将

多行合并成一行：

）