##About
Datediff() is one of the functions in expression. This page shows how to use datediff().
##Syntax
datediff( datepart , startdate , enddate )
datediff( datepart , startdate , enddate ) calculates the difference between enddate and startdate in the unit of datepart.
##Argument
###datepart Is the part of startdate and enddate that specifies the type of boundary crossed. The following table lists all valid datepart arguments. User-defined variable equivalents are not valid.
| datepart | Abbreviations |
|---|---|
| year | yy, yyyy |
| quarter | qq, q |
| month | mm, m |
| dayofyear | dy, y |
| day | dd, d |
| week | wk, ww |
| hour | hh |
| minute | mi, n |
| second | ss, s |
| millisecond | ms |
| microsecond | mcs |
| nanosecond | ns |
###startdate Is an expression that can be resolved to a time, date, smalldatetime, datetime, datetime2, or datetimeoffset value. date can be an expression, column expression, user-defined variable or string literal. startdate is subtracted from enddate. To avoid ambiguity, use four-digit years.
###enddate See startdate.
##Example
###Expression applied to the third column. The below expression does calculation shippeddate - orderdate in week. (Expression type doesn't necessarily have to be 'string' as below).
###1st argument of datediff() has changed to month. Thus the below expression does shippeddate - orderdate in month.
