T-SQL 101: #58 Subtracting dates and times in SQL Server T-SQL using DATEDIFF

When you’re working with T-SQL, it’s common to need to work out how far apart two dates and or times are. Look at the query below:

In this case I'm asking how many days is it from 28th of February 2019 to 31st of July 2019? And if look at the answer:

We can see that it’s 153 days.

Now I used days here but now we could have used any of those other intervals that I discussed when we looked at DATEADD. So I could work at how many minutes that was or how many seconds that was between the two times. I could even say how many months?

The order of the parameters that you pass to this function are important. The first one is considered the starting date and/or time, and the second is the ending date and/or time. So if I had put those around the other way, I would have seen -153 instead of 153.

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