SYSDATE FAQS

 1. What is SYSDATE in Oracle?

• SYSDATE is a built-in function in Oracle that returns the current date and time according to the database server's system clock.

2. What data type does SYSDATE return?

• SYSDATE returns a DATE data type in Oracle, which includes both the date and time.

3. Does SYSDATE include the time?

• Yes, SYSDATE includes both the date and the time. The default format for displaying SYSDATE is DD-MON-YY HH24:MI:SS.

4. Is `SYSDATE affected by the session’s time zone?

• No, SYSDATE returns the system’s current date and time, which is based on the database server’s system clock, not the session’s time zone.

5. What is the difference between SYSDATE and CURRENT_DATE?

• SYSDATE: Returns the current date and time of the database server’s system clock.
• CURRENT_DATE: Returns the current date and time according to the session's time zone.

6. How can I extract the year, month, or day from SYSDATE?

• You can use the EXTRACT function to get specific components from SYSDATE. For example:
• Extract the year:

o   SELECT EXTRACT(YEAR FROM SYSDATE) FROM dual;

• Extract the month:

o   SELECT EXTRACT(MONTH FROM SYSDATE) FROM dual;

7. Can I perform arithmetic with SYSDATE?

• Yes, you can perform date arithmetic with SYSDATE. For example:
• Adding 5 days:

o   SELECT SYSDATE + 5 FROM dual;

• Subtracting 3 hours:

o   SELECT SYSDATE - INTERVAL '3' HOUR FROM dual;

8. Does `SYSDATE change during the execution of a query?

• Yes, SYSDATE will return a different value if the system clock changes between multiple executions of a query, as SYSDATE fetches the current time whenever it is called.

9. Can I use SYSDATE for calculating the difference between dates?

• Yes, you can calculate the difference between SYSDATE and another date (like a hire date) by subtracting one from the other. For example:

·        SELECT SYSDATE - hire_date AS days_since_hire FROM employees;

10. How do I get just the current time using SYSDATE?

• While SYSDATE returns both date and time, you can extract the time portion using TO_CHAR or other date functions. For example:

·        SELECT TO_CHAR(SYSDATE, 'HH24:MI:SS') FROM dual;

11. What is the difference between SYSDATE and SYSTIMESTAMP?

• SYSDATE returns a DATE type that includes the current date and time but without time zone information.
• SYSTIMESTAMP returns a TIMESTAMP WITH TIME ZONE data type, which includes the current date, time, and time zone information.

12. Can I set SYSDATE to a specific value?

• No, SYSDATE is a system function that always returns the current date and time. It cannot be manually set to a specific value.

13. What is the time zone for SYSDATE?

• The time zone for SYSDATE is the time zone of the database server's operating system, not the user’s session.

14. Can I use SYSDATE in WHERE clauses?

• Yes, SYSDATE is commonly used in WHERE clauses to filter rows based on the current date or time. For example:

·        SELECT * FROM orders WHERE order_date > SYSDATE - 7;

15. Does `SYSDATE account for daylight saving time?

• SYSDATE reflects the current system time, which means if the operating system accounts for daylight saving time, so will SYSDATE.

If you have more specific questions about SYSDATE, feel free to ask!