oracle| Comparison | data | data type
Original Author: James Koopmann
The format of the timestamp data is the same as the date data. Note that the TO_CHAR function supports date and timestamp, but Trunc does not support timestamp data types. This has made it clear that using the timestamp data type is more accurate than the date data type when the difference between two times is extremely important.
If you want to display timestamp decimal seconds information, refer to the following:
In the example above, I'm only realistic about 3 bits after the decimal point.
It is easier to calculate the data differences between timestamp than the old date data type. When you subtract directly, see what happens. The results will be easier to understand, the first line of 17 days, 18 hours, 27 minutes and 43 seconds.
This means no longer needing to care about how many seconds a day is in trouble calculations. Therefore, getting the number of days, months, days, hours, minutes and seconds becomes a matter of extracting numbers with the SUBSTR function.
System date and Time
Returns the date data type in order to get the system time. You can use the Sysdate function.
Sql> SELECT sysdate from DUAL;
To get the system time, return to the timestamp data type. You can use the Systimpstamp function.
Sql> SELECT Systimestamp from DUAL;
You can set initialization parameters fixed_date Specify the Sysdate function to return a fixed value. This is used in the test date and time sensitive code. Note that this parameter is not valid for the Systimestamp function.
sql> ALTER SYSTEM SET fixed_date = ' 2003-01-01-10:00:00 ';
When using date and timestamp types, the choice is clear. You are free to dispose of date and timestamp types. When you try to switch to a more powerful timestamp, you need to be aware that they have a similar place, and there are different places, and it's enough to cause damage. Both in terms of simplicity and spacing size each have advantages, please choose reasonably.
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