How do you use the datediff function in SQL?

2 years ago
Olivia Parker
2 minutes

The DATEDIFF function in SQL is used to calculate the difference between two dates, returning the time interval between the two dates.

The basic syntax of the DATEDIFF function is as follows: DATEDIFF(datepart, startdate, enddate)

datepart represents the unit used to calculate time intervals, and can be one of the following values:

  1. year: calendar year
  2. quarter: a period of three months.
  3. month: a period of time on the calendar consisting of approximately 30 or 31 days
  4. duration: period of time
  5. week number
  6. number of hours
  7. minute: number of minutes
  8. second: the amount of time in seconds
  9. millisecond: a unit of time equal to one thousandth of a second.

startdate and enddate represent two dates that need to be calculated for the time interval. They can be columns names in date format, variables, or directly input date values.

For instance, calculate the number of days between two dates:
SELECT DATEDIFF(day, ‘2022-01-01’, ‘2022-02-01’);

The result of the calculation in the above example is 31, indicating a time difference of 31 days between January 1, 2022 and February 1, 2022.

It is important to note that the DATEDIFF function calculates the difference between two dates without considering specific time values. If you need to take into account the time part, other functions such as DATEPART can be used in conjunction with the DATEDIFF function for calculation.

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