1. I want to show the employees that were hired in the month of May.
select FIRST_NAME from EMPLOYEES where HIRE_DATE=?????
2.There is another query that employees ask me that do not have a commission but where I do COMMISSION_PCT = null or '' but it does not work for me if there is some simpler way to do it.
For the May date:
SELECT FIRST_NAME
FROM EMPLOYEES
WHERE HIRE_DATE BETWEEN TO_DATE ('2018/05/01', 'yyyy/mm/dd')
AND TO_DATE ('2018/05/31', 'yyyy/mm/dd');
For the commission:
SELECT *
FROM EMPLOYEES
WHERE COMMISION_PCT IS NULL
To get the month in oracle you can use an extract something like this:
select FIRST_NAME from EMPLOYEES where extract(month from HIRE_DATE) = 5
and for the other query, try
COMMISSION_PCT is null