Modify the query select 'John Smith' from DUAL;. This time, use the SUBSTR function to extract a substring that represents your last name from the text string 'your_first_name your_last_name'. Assume you know the number of characters you need to extract.

Modify the query select 'John Smith' from DUAL; . This time, use the INSTR and SUBSTR functions to extract a substring that represents your first name from the text string 'your_first_name your_last_name'. Assume you do not know the number of characters to extract.

Modify the query select 'John Smith' from DUAL; . This time, use the INSTR, SUBSTR, and LENGTH functions to extract a substring that represents your last name from the text string 'your_first_name your_last_name'. Assume you do not know the number of characters you need to extract.