LAST_DAY FAQS

 1. What does the LAST_DAY function do in Oracle?

• The LAST_DAY function returns the last day of the month for a given date. It can be used with DATE, TIMESTAMP, or TIMESTAMP WITH TIME ZONE types.

 

2. What is the syntax for the LAST_DAY function?

• The syntax is:

·        LAST_DAY(date)

• date: A DATE, TIMESTAMP, or TIMESTAMP WITH TIME ZONE value from which you want to find the last day of the month.

 

3. What is the return type of LAST_DAY?

• The return type is a DATE value, representing the last day of the month of the given date. The time is set to 23:59:59.

 

4. How does LAST_DAY handle leap years?

• The LAST_DAY function automatically adjusts for leap years. For example, in leap years, February 29 is considered the last day of the month.

Example:

SELECT LAST_DAY(DATE '2024-02-15') FROM dual;

-- Result: 2024-02-29

 

5. What happens if I use a TIMESTAMP with LAST_DAY?

• If you pass a TIMESTAMP value, the function returns the last day of the month, with the time set to 23:59:59 in the session's time zone.

Example:

SELECT LAST_DAY(TIMESTAMP '2025-03-10 14:30:00') FROM dual;

-- Result: 2025-03-31 23:59:59

 

6. Can LAST_DAY be used with SYSDATE?

• Yes, you can use SYSDATE to get the last day of the current month. This is useful for generating month-end reports.

Example:

SELECT LAST_DAY(SYSDATE) FROM dual;

-- Result: (Last day of the current month)

 

7. How does LAST_DAY handle time zones when using TIMESTAMP WITH TIME ZONE?

• LAST_DAY ignores the time zone information when processing TIMESTAMP WITH TIME ZONE and returns the last day of the month in the session's time zone.

 

8. Does LAST_DAY work with intervals?

• No, the LAST_DAY function doesn't directly work with intervals. It only returns the last day of the month for a given date. You may need to use other date arithmetic functions for complex interval calculations.

 

9. Can I use LAST_DAY to find the last day of a specific quarter or year?

• Yes, LAST_DAY can be used in conjunction with other date functions to find the end of a quarter or year by passing a date corresponding to that period.

Example:

SELECT LAST_DAY(DATE '2025-03-15') FROM dual;

-- Result: 2025-03-31 (End of Q1)

 

10. What happens if I pass an invalid date to LAST_DAY?

• If an invalid date is passed, Oracle will raise an error, such as ORA-01830: date format picture ends before converting entire input string.

 

11. Does LAST_DAY account for different month lengths?

• Yes, the LAST_DAY function accounts for varying month lengths (28, 29, 30, 31 days) and returns the correct last day based on the calendar month.

 

12. Can I use LAST_DAY with INTERVAL values or specific periods?

• While LAST_DAY doesn't work directly with intervals, you can combine it with other date functions or intervals for more complex calculations. For example, you can subtract days from the result of LAST_DAY to find the last day of a previous month.

Example:

SELECT LAST_DAY(SYSDATE) - INTERVAL '1' MONTH FROM dual;

-- Result: The last day of the previous month

 

13. How can I find the last business day of the month using LAST_DAY?

• To find the last business day, you can combine LAST_DAY with NEXT_DAY or PREVIOUS_DAY functions, depending on your business rules.

Example (Finding last business day):

SELECT NEXT_DAY(LAST_DAY(SYSDATE), 'FRIDAY') FROM dual;

-- Result: Last Friday of the month

 

14. Does LAST_DAY work with all date formats?

• LAST_DAY works with all DATE, TIMESTAMP, or TIMESTAMP WITH TIME ZONE formats. However, the input date should be valid, and the format should be compatible with the Oracle database's date/time settings.

 

15. Can I calculate the last day of the month based on a custom date format?

• Yes, you can use TO_DATE to convert a custom string into a DATE or TIMESTAMP, and then use LAST_DAY to get the last day of the month for that custom date.

Example:

SELECT LAST_DAY(TO_DATE('2025-04-15', 'YYYY-MM-DD')) FROM dual;

-- Result: 2025-04-30