Fetching value from chiled table in doctype for custome field in onther doctype

hello all ;

I want a way to make a custom script for fetching value of a certain value through a table in another doctype based on another field in the same doc type

when i make custom field in delivery note beside transporter name to fetch value of amount transport based on territory from prices in custom chilled table under supplier form

any one can help me ?

Hope this helps