| Excerpt |
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Calculates the difference between two valid date values for the specified units of measure. |
- Inputs must be column references.
- The first value is used as the baseline to compare the date values.
- Results are calculated to the integer value that is closest to and lower than the exact total; remaining decimal values are dropped.
| D lang syntax |
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| RawWrangle | true |
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| Type | ref |
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| showNote | true |
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| WrangleText | derive type:single value:datedif(StartDate, EndDate, month) |
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datedif(StartDate, EndDate, month) |
Output: Returns the number of full months that have elapsed between StartDate and EndDate.
| D lang syntax |
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| RawWrangle | true |
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| Type | syntax |
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| showNote | true |
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| WrangleText | derive type:single value:datedif(date1,date2,date_units) |
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datedif(date1,date2,date_units) |
| Argument | Required? | Data Type | Description |
|---|
| date1 | Y | datetime | Starting date to compare |
| date2 | Y | datetime | Ending date to compare |
| date_units | Y | string | String literal representing the date units to use in the comparison |
date1, date2
Date values to compare using the date_units units. If date2 > date1, then results are positive.
- Date values must be column references.
- If
date1 and date2 have a specified time zone offset, the function calculates the difference including the timezone offsets. - If
date1 does not have a specified time zone but date2 does, the function uses the local time in the same time zone as date2 to calculate the difference. The functions returns the difference without the time zone offset.
| Required? | Data Type | Example Value |
|---|
| Yes | String (Date column reference) | LastContactDate |
date_units
Unit of date measurement to calculate between the two valid dates.
| Required? | Data Type | Example Value |
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| Yes | String | year |
Accepted Value for date units:
yearquartermonthdayofyear
weekdayhourminutesecondmillisecond
Example - aged orders
| Include Page |
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| EXAMPLE - DATEDIF Function |
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| EXAMPLE - DATEDIF Function |
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|
Example - dayofyear Calculations
This example demonstrates how dayofyear is calculated using the DATEDIF function, specifically how leap years and leap days are handled. Below, you can see some example dates. The year 2012 was a leap year.
Source:
| dateId | d1 | d2 | Notes |
|---|
| 1 | 1/1/10 | 10/10/10 | Same year; no leap year |
| 2 | 1/1/10 | 10/10/11 | Different years; no leap year |
| 3 | 10/10/11 | 1/1/10 | Reverse dates of previous row |
| 4 | 2/28/11 | 4/1/11 | Same year; no leap year; |
| 5 | 2/28/12 | 4/1/12 | Same year; leap year; spans leap day |
| 6 | 2/29/12 | 4/1/12 | Same year; leap year; d1 = leap day |
| 7 | 2/28/11 | 2/29/12 | Diff years; d2 = leap day; converted to March 1 in d1 year |
Transformation:
In this case, the transform is simple:
| D trans |
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| RawWrangle | true |
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| p03Value | 'datedifs' |
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| Type | step |
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| WrangleText | derive type:single value:datedif(d1,d2,dayofyear) as:'datedifs' |
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| p01Name | Formula type |
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| p01Value | Single row formula |
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| p02Name | Formula |
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| p02Value | datedif(d1,d2,dayofyear) |
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| p03Name | New column name |
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| SearchTerm | New formula |
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|
Results:
| dateId | d1 | d2 | datedifs | Notes |
|---|
| 1 | 1/1/10 | 10/10/10 | 282 | Same year; no leap year |
| 2 | 1/1/10 | 10/10/11 | 282 | Different years; no leap year |
| 3 | 10/10/11 | 1/1/10 | -282 | Reverse dates of previous row |
| 4 | 2/28/11 | 4/1/11 | 32 | Same year; no leap year; |
| 5 | 2/28/12 | 4/1/12 | 33 | Same year; leap year; spans leap day |
| 6 | 2/29/12 | 4/1/12 | 32 | Same year; leap year; d1 = leap day |
| 7 | 2/28/11 | 2/29/12 | 1 | Diff years; d2 = leap day; converted to March 1 in d1 year |
Rows 1 - 3:
- Row 1 provides the baseline calc.
In Row 2, the same days of the year are used, but the year is different by a count of 1. However, since we are computing dayofyear the result is the same as for Row 1.
| Info |
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NOTE: When computing dayofyear, the year value for d2 is converted to the year of d1. The difference is then computed. |
Row 3 represents the reversal of dates in Row 2.
| Info |
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NOTE: Negative values for a dayofyear calculation indicate that d2 occurs earlier in the calendar than d1, ignoring year. |
Rows 4 - 7: Leap years
- Row 4 provides a baseline calculation for a non-leap year.
Row 5 uses the same days of year as Row 4, but the year (2012) is a leap year. Dates span a leap date (February 29). Note that the DATEDIF result is 1 more than the value in the previous row.
| Info |
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NOTE: When the two dates span a leap date and the year for d1 is a leap year, then February 29 is included as part of the calculated result. |
- Row 6 moves date 1 forward by one day, so it is now on a leap day date. Result is one less than the previous row, which also spanned leap date.
Row 7 switches the leap date to d2. In this case, d2 is converted to the year of d1. However, since it was a leap day originally, in the year of d1, this value is March 1. Thus, the difference between the two dates is 1.
| Info |
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NOTE: If d2 is a leap date and the year for d1 is not a leap year, the date used in for d2 is March 1 in the year of d1. |
