What is the meaning of the following SQL Server declaration: datetime2(7)?

问题

Inside a SQL Server query, there is: datetime2(7).
I know datetime2, but I don't understand (7).

Can you explain the meaning of (7)?

回答1:

datetime2 [ (fractional seconds precision) ]

It's the fractional seconds precision according to the MSDN documentation.

http://msdn.microsoft.com/en-us/library/bb677335.aspx

This is the microsoft example of 4:

DECLARE @datetime2 datetime2(4) = '12-10-25 12:32:10.1234';

So I would assume that 7 would be:

DECLARE @datetime2 datetime2(7) = '12-10-25 12:32:10.1234567';

来源：https://stackoverflow.com/questions/17260503/what-is-the-meaning-of-the-following-sql-server-declaration-datetime27