Converting number with leading zeros in integer in QGIS

Question

I used this command to organize my treenumbers:

lpad("baumnummer", 6, '0')

So tree number 1 will be shown as "00001". I did this because in my layout lists every tree will be put into the right order.

Now I found another solution but I want to remove all the zeros beforehand from my Attribute table. How can I achieve that?

Answer 1

Try this expression with the to_int() function:

to_int("baumnummer")
-- to_int('000001') -> 1

If you wish to maintain the string field type, you could expand the expression above with the to_string() function to:

to_string(to_int("baumnummer"))
-- to_string(to_int('000001')) -> '1'

Additionally one can achieve the desired output with the format_number() function:

format_number("baumnummer",0,'de')
-- format_number('000001',0,'de') -> '1'