once we click on any of these leads their respective project's id shld b displayed under board keys

[venugopal Capgemini]

i have 2 dropdowns i want to link these 2 dropdowns using jql

once we click on any of these leads their respective project's id shld b displayed under board keys means once we we click on 1st dropdown  2nd dropdown list will be displayed automatically

[Nic Brough -Adaptavist-]

This sounds like it should be a cascading-select list custom field.