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## Adjusting Datetime Field for Daylight Savings Time

Published: 06 Aug 2014
Last Modified Date: 03 Jan 2019

### Question

How to adjust a Datetime field to include Daylight Savings Time adjustments when the data source does not provide this functionality.

Tableau Desktop

### Answer

Use a calculated field similar to the following, where [Order Date] is the Datetime field that is being adjusted:
```IF [Order Date] >= DATEADD('hour', 2,
(IF DATEPART('weekday', DATEADD('month', 2, DATETRUNC('year', [Order Date]))) = 1
THEN DATEADD('month', 2, DATETRUNC('year', [Order Date])) + 7
ELSE DATETRUNC('week', DATEADD('month', 2, DATETRUNC('year', [Order Date])) + 13) END))

AND [Order Date] < DATEADD('hour', 2,
(IF DATEPART('weekday', DATEADD('month', 10, DATETRUNC('year', [Order Date]))) = 1
THEN DATEADD('month', 10, DATETRUNC('year', [Order Date]))
ELSE DATETRUNC('week', DATEADD('month', 10, DATETRUNC('year', [Order Date])) + 6) END))

THEN DATEADD('hour', 1, [Order Date])

ELSE [Order Date] END```
For European time changes use a formula similar to the following:
```IF
//last Sunday in March at 1AM
[Date] >= DATEADD('hour',1,DATEADD('day',-1,DATETRUNC('week',DATEADD('month',3,DATETRUNC('year',[Date])))))
AND
//last Sunday in October at 2AM
[Date] < DATEADD('hour',2,DATEADD('day',-1,DATETRUNC('week',DATEADD('month',10,DATETRUNC('year',[Date])))))
THEN DATEADD('hour',1,[Date])
ELSE [Date]
END```
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