Datepart - Is the parameter that specifies on which part of the date to return a new value. Some of the supported types are ...

Datepart - Is the parameter that specifies on which part of the date to return a new value. Some of the supported types are year(yy, yyyy), month (mm, m)and dayofyear(dy, y). For complete supported list see Books Online. Number - Is the value used to increment datepart. Date - Is an expression that returns a datetime value, or a character string in a date format.