Which statement is true about the Oracle SQL, DELETEand TRUNCATEstatements?

Which two statements are true regarding the SQL GROUP BY clause?

Which two are true about dropping columns from a table?

Examine the commands used to create DEPARTMENT_DETAILSand COURSE_DETAILS tables:

You want to generate a list of all department IDs that do not exist in the COURSE_DETAILStable.
You execute the SQL statement:

What is the outcome?

View the exhibit and examine the description of the DEPARTMENTSand EMPLOYEEStables.

The retrieve data for all the employees for their EMPLOYEE_ID, FIRST_NAME, and DEPARTMENT NAME, the following SQL statement was written:
SELECT employee_id, first_name, department_name
FROM employees
NATURAL JOIN departments;
The desired output is not obtained after executing the above SQL statement. What could be the reason for this?