# dateDiff


`dateDiff` returns the difference in days between two date fields. If you include a value for the period, `dateDiff` returns the difference in the period interval, rather than in days.

## Syntax


```
dateDiff(date1, date2,[period])
```

## Arguments


`dateDiff` takes two dates as arguments. Specifying a period is optional.

 *date 1*   
The first date in the comparison. A date field or a call to another function that outputs a date. 

 *date 2*   
The second date in the comparison. A date field or a call to another function that outputs a date. 

 *period*   
The period of difference that you want returned, enclosed in quotes. Valid periods are as follows:  
+ YYYY: This returns the year portion of the date.
+ Q: This returns the date of the first day of the quarter that the date belongs to. 
+ MM: This returns the month portion of the date.
+ DD: This returns the day portion of the date.
+ WK: This returns the week portion of the date. The week starts on Sunday in Amazon Quick.
+ HH: This returns the hour portion of the date.
+ MI: This returns the minute portion of the date.
+ SS: This returns the second portion of the date.
+ MS: This returns the millisecond portion of the date.

## Return type


Integer

## Example


The following example returns the difference between two dates.

```
dateDiff(orderDate, shipDate, "MM")
```

The following are the given field values.

```
orderDate          shipdate
=============================
01/01/18            03/05/18
09/13/17            10/20/17
```

For these field values, the following values are returned.

```
2
1
```