Summary of the time functions of SQL Server

1. Get the system Current time: Sysdatetime () and getdate () function. The difference is just not the same precision

2. DatePart (), DateDiff (), DateAdd ().

Example: SELECT DATEADD (year, DATEDIFF (year,-1, Sysdatetime ()),-1); Results: 2014-12-31 00:00:00.000, including system current time: 2014-08-18 19:20:58.6096869

Analysis: DATEDIFF (year,-1, Sysdatetime ()) results: 115. Because starting from 1990. 0--1990 years, -1--1989 years. DateDiff for the latter parameter minus one parameter, 114-( -1) =115.dateadd is added to the last two parameters: 115+ (-1) =114=2014 year, two functions are calculated in the first argument.

The SELECT DATEPART (weekday,getdate ()) result is 2, the current time is Monday, and 2 is the second day of the week.