Adding days in date using QGIS Field Calculator

Question

I'd like to create a new field adding 10 days in a date (string format) in QGIS; using the Field Calculator. For example, in the field_1 there is 22/02/2021, in field_new it should become 04/03/2021.

Maybe, I should convert date in number, as you can see in Excel.

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Any suggestion?

• Kadir Şahbaz: What is type of the date field? String or Date?
• Mark: "field_1" is a string, also "field_new" will be a string

Answer 1

You can use something like:

format_date(to_date("field_1",'dd/MM/yyyy')+to_interval('10 Days'),'dd/MM/yyyy')

First you need to convert your string to a date (the to_date() function), so you can add a datetime interval. The format_date() is needed, because the result of + to_interval() will return a datetime format. So you convert the result back to a date only and use your previous date-format as string (dd/MM/yyyy instead of yyyy-MM-dd).

Answer 2

For string-typed target field:

to_string( to_date( "field_1" , 'dd/MM/yyyy' ) + to_interval( '10 days' ) )

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For date-typed target field:

to_date( to_date( "field_1" , 'dd/MM/yyyy' ) + to_interval( '10 days' ) )

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