EXTRACT FAQS

 1. What does the EXTRACT function do in Oracle?

• The EXTRACT function is used to extract specific components (like year, month, day, hour, minute, second, etc.) from a DATE, TIMESTAMP, or INTERVAL. It returns a numeric value representing the requested date or time part.

 

2. What is the syntax of the EXTRACT function?

• The syntax is:

·        EXTRACT (date_part FROM date_value)

• date_part: The component to extract (e.g., YEAR, MONTH, DAY, HOUR, etc.).
• date_value: The DATE, TIMESTAMP, or INTERVAL value from which to extract the component.

 

3. What types of date parts can I extract using EXTRACT?

• You can extract the following date parts:
• YEAR, MONTH, DAY, HOUR, MINUTE, SECOND
• TIMEZONE_HOUR, TIMEZONE_MINUTE
• WEEK, DOW (Day of the Week), ISO_WEEK, DAYOFYEAR
• QUARTER

 

4. Can EXTRACT be used with TIMESTAMP values?

• Yes, EXTRACT works with both DATE and TIMESTAMP values, and it can extract the same components from both types. For TIMESTAMP, it can also include time components (like hour, minute, and second).

 

5. What is the return type of EXTRACT?

• The return type is a numeric value corresponding to the extracted part (for example, the year as a number, the month as an integer, etc.).

 

6. Can I use EXTRACT with TIMESTAMP WITH TIME ZONE?

• Yes, EXTRACT can be used with TIMESTAMP WITH TIME ZONE to extract date and time components, including time zone information (like TIMEZONE_HOUR and TIMEZONE_MINUTE).

 

7. How does EXTRACT work with INTERVAL data types?

• EXTRACT can also be used with INTERVAL types (like INTERVAL YEAR TO MONTH or INTERVAL DAY TO SECOND). For example, you can extract the year or month part from an interval.

 

8. Can I extract the weekday or ISO week number with EXTRACT?

• Yes, EXTRACT supports extracting the day of the week (DOW), week number (WEEK), and ISO week number (ISO_WEEK) from a DATE or TIMESTAMP.

 

9. How does EXTRACT handle leap years or different month lengths?

• The EXTRACT function handles leap years and varying month lengths automatically. For example, if you extract the month from a date in February of a leap year, it will correctly return 2.

 

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

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

 

11. Can I use EXTRACT to get a specific quarter of the year?

• Yes, you can use EXTRACT(QUARTER FROM date_value) to get the quarter (1 to 4) from a date or timestamp.

Example:

SELECT EXTRACT(QUARTER FROM DATE '2025-07-10') FROM dual;

-- Result: 3 (for Q3)

 

12. Does EXTRACT work with SYSDATE?

• Yes, you can use EXTRACT with SYSDATE to retrieve the current year, month, day, etc., from the current system date.

Example:

SELECT EXTRACT(MONTH FROM SYSDATE) FROM dual;

-- Result: (current month)

 

13. What happens if I try to extract a part that is not available?

• If you try to extract an unsupported part from a DATE or TIMESTAMP (for example, extracting hours from a DATE column), Oracle will return an error or unexpected result. Always ensure that the date part you're trying to extract exists for the provided value.

 

14. Can EXTRACT be used with CURRENT_TIMESTAMP?

• Yes, you can use EXTRACT with CURRENT_TIMESTAMP to retrieve specific components of the current timestamp, including the date, time, and time zone information.

Example:

SELECT EXTRACT(HOUR FROM CURRENT_TIMESTAMP) FROM dual;

-- Result: (current hour)

 

15. Can I use EXTRACT for time zone calculations?

• Yes, you can use EXTRACT to extract the time zone hour and minute from a TIMESTAMP WITH TIME ZONE value, which can be useful for calculating time zone differences or offsets.

Example:

SELECT EXTRACT(TIMEZONE_HOUR FROM TIMESTAMP '2025-07-10 14:30:00 -07:00') FROM dual;

-- Result: -7 (time zone offset in hours)

 

16. How accurate is EXTRACT when dealing with time values?

• EXTRACT is accurate in returning the specified part of a date, timestamp, or interval. However, it always returns a numeric value, and the exact representation (such as time or date component) may vary based on the data type.

 

17. Can I use EXTRACT to calculate the difference between two dates?

• While EXTRACT alone cannot calculate differences, you can use it in combination with other date arithmetic functions to extract specific components of the difference (e.g., extracting years, months, or days between two dates).