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  • Bernard K

DATETRUNC () Function in Tableau


datetrunc function in tableau

Introduction

DATETRUNC function is used to truncate a specific date into the accuracy specified by the date part.

Syntax: DATETRUNC (date part, date, [start-of-week])

E.g., DATETRUNC (‘quarter’, [Order Date], ‘Sunday’) -> which truncates the date field to the first day of each quarter, with Sunday being taken as the start of the week.

DATETRUNC (‘month’, [Order Date]) -> This function truncates the date field to the first day of each month, with the start of the week assuming the day configured in the data source.

You can edit/configure your data source week start by,

Right-clicking on the data source -> Date Properties…

configuring data source start week

(Note: If the start of the week is omitted in the DATETRUNC calculation, the week start day is determined by the start day configured in the data source).

Variations of the DATETRUNC function

Below see the results of the DATETRUNC function.

DATETRUNC (date part, Order Date) – when date part is applied as week, month, quarter, and year respectively.

results of the datetrunc function

(All dates are truncated to the first day of each date part)

Application of the DATETRUNC function

One of the ways in which I apply the DATETRUNC function is when creating a stepped line chart. For example, I can create a stepped line chart visualizing Sales by month…. By first calculating sales generated in each month by simply combining a FIXED LOD & a DATETRUNC function.

Fixed LOD plus datetrunc function

(This calculation truncates the Order Date to the first day of each month, then evaluates the sales generated in each of the month).

To build the view (stepped line chart)

  • Right-drag Order Date to the column shelf à Order Date (Continuous)

  • Add the calculation ‘Sales by month’ to the row shelf

using datetrunc function to created a stepped line chart

(Which creates the stepped line chart above by plotting the monthly sales value on the first day of the month, while repeating the same value for the remainder days of the month – forming a horizontal gap/line between one month to the next)

Conclusion

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About Me

More About the Author

Bernard K

Analytics Consultant | 3X Tableau Certified

Bernard is a data analytics consultant helping businesses reveal the true power of their data and bring clarity to their reporting dashboards. He loves building things and sharing knowledge on how to build dashboards that drive better outcomes.

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