DATETIMEis an eight-byte datatype which stores both a date and time in one column, with an accuracy of three milliseconds. As we’ll see though, the distribution of this granularity may not be exactly what we’d expect.
DATETIMEvalues are January 1, 1753 00:00:00.000, through December 31, 9999 23:59:59.997. On older databases designed prior to SQL Server 2008, because there was no explicit support for date values, it was sometimes customary to leave off the time portion of a
DATETIMEvalue, and have it default to midnight on that morning. So for example today would be stored as
February 21, 2018 00:00:00.000.
If you’re not particularly familiar with SQL Server data types, this is detailed enough information to get you going and to explain exactly why you shouldn’t use DATETIME anymore…