SQL Server DateTime2（0）与日期

Question

What are the implications of using SQL Server's DateTime2 with a precision of 0 to represent a date rather than the built in Date field.

In either case, my concern is to prevent accidental time entries, but are there storage or performance considerations I should take note of?

Answer 1

DateTime2(0) will store datetime with no decimal values ie YYYY-MM-DD hh:mm:ss

SELECT CONVERT(DateTime2(0) , GETDATE())
RESULT: 2015-04-06 20:47:17

Storing data just as dates will only store dates ie YYYY-MM-DD without any time values.

SELECT CONVERT(Date , GETDATE())
RESULT:  2015-04-06

If you are only interested in dates then use DATE data type.

DATETIME2 will use 6 bytes for precisions less than 3 and DATE will use 3 bytes .

Date is half the size of DATETIME(0) hence it will also perform better since sql server will process less data and will save disk space as well.

Answer 2

It won't work. According to MSDN the minimum size of Datetime2 is six bytes and will contain hh:mm:ss so it can, and will, contain a time component (default of midnight). As other responders have noted you must use a date type to guarantee that not time portion is saved and will occupy three bytes.

https://technet.microsoft.com/en-us/library/bb677335%28v=sql.105%29.aspx