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POSTGRESQL DATEDIFF MILLISECONDS HOW TO
POSTGRESQL DATEDIFF MILLISECONDS SOFTWARE
POSTGRESQL DATEDIFF MILLISECONDS CODE

POSTGRESQL DATEDIFF MILLISECONDS HOW TO

How to Find PostgreSQL DateDiff using Extract() Let’s check some of the examples and find the date differences. To get the same functionality as DATEDIFF, you can use the minus (-) operator with different functions such as EXTRACT(), DATE_PART() and etc, to find the difference between the two dates. But this kind of function doesn’t exist in PostgreSQL.

POSTGRESQL DATEDIFF MILLISECONDS SOFTWARE

There is a function called DATEDIFF in other database software such as Oracle, SQL and etc, to compute the difference between the two dates.

How to Find PostgreSQL DateDiff using Age().

How to Find PostgreSQL DateDiff using DATE_PART().

How to Find PostgreSQL DateDiff using Extract().

Do you want the result to be 1, or 0, or perhaps 0.5? Depending on your need, you can then use millisecond for the datepart parameter, divide by 1000, and then either round, truncate, or display it as-is. As a thought experiment, ask yourself what you want the result to be when the two values are exactly 500 milliseconds apart. seconds of a given minute to 00.000000000. Rather, it counts the number of times you have to pass from 59.99999999. It doesn't count the number of seconds or milliseconds between the data and then truncate or round it. You can see the same behavior if you use minute for the datepart parameter. It might help to think of a second-boundary as what you have to cross to get from.

Rather, it looks to see how many times you have to cross a second-boundary to get from startdate to enddate. It does not calculate the precise number of milliseconds between two dates and then convert, via either truncation or rounding, to seconds. The fact that your data is of millisecond granularity doesn't have anything to do with "being adjacent".ĭATEDIFF returns a count (as a signed integer value). Refers to the sample data that the documentation uses to demonstrate that DATEDIFF returns a value of 1 when the difference between the start date and the end date cross one boundary. Those dates are adjacent and they differ in time by a hundred nanoseconds (.0000001 second). Which way would you recommend to write the second calculation if one cares about accurately rounded results and is open for the best performing solution? Why is that so? It is astonishing that the same command with the MILLISECOND option returns a precise amount of seconds but with the SECOND option it does not.

ROUND(DATEDIFF(MILLISECOND, startDateTime, endDateTime) / 1000.0, 0) AS resultSecondsExtractedFromMilliseconds,ĭATEDIFF(MILLISECOND, startDateTime, endDateTime) AS resultDatediffMilliseconds

POSTGRESQL DATEDIFF MILLISECONDS CODE

Here's the code for the example: WITH cteValues ASĬAST(startDateTime AS DATETIME) AS startDateTime,ĬAST(endDateTime AS DATETIME) AS endDateTime Please have a look at rows with id 8 and 9 as well as 10 and 11 in the following result set: It seams that if a boundary to the next minute is crossed the value of DATEDIFF(SECONDS.) always yields 1 while for the same interval all within one minute the seconds yield 0. Does that also qualify as "being adjacent"? It mentions something about "datepart boundaries" stating that "Those dates are adjacent and they differ in time by a hundred nanoseconds (.0000001 second).

I read the MSDN Documentation but didn't get any wiser.

I started with the simplistic expression DATEDIFF(SECOND, startDateTime, endDateTime) and assumed that it might return 0 seconds for up to 499 (in fact due to precision 497) milliseconds and round up to 1 second for values starting at 500 milliseconds. The two datetimes typically lie pretty close to another (differences measured between 0.4 and 2 seconds). The goal is to return the number of seconds between two different datetime values. I am puzzled by the following behaviour in SQL Server (tested on SQL Server 2017).