Dropdown list (+30) how to make a parameter

hello everyone, do you know how to make the number (???) in the drop down list? I have a database of ads and I filter them by cities. The user can select a city and see an ad there, how can I make the number of ads belong to the name of the city in the drop-down list? example : New-York (213) where 213 is the number of ads in this name (city)

In the Cities collection add a text field, call it ‘Lookup’
Everytime an add is created update the City > Lookup = City name & (Count of ads)
*you may have to do (count of ads) + 1

Make your dropdown reference 'Lookup"

When an add is deleted you have to do an update to the ‘Lookup’ field to get an accurate count.

hi, that sounds interesting i will do it soon and let you know whether i have achieved it or not