问题
I am new to CRM. I have a requirement where I have an "account" entity and a "contact" entity. In contact form I have a lookup field for searching account name which is stored in account entity. When I select an organization through lookup, the contact number of that organization should be fetched and saved in another field in contact form. I need to do it with fetch XML.
回答1:
Option 1: You can do a no-code solution by mapping fields between account & contact.
Option 2: If you don't want a physical copy of field value in both entity, use Quick view form of Account lookup to just display the fields in contact without storing redundant data.
Option 3: If you still want to store the value onchange of account, retrieve it & set it in contact field. This step by step guide will help you to build fetchxml & use it in JS. Your question doesn't say if you are stuck in query or any error.
来源：https://stackoverflow.com/questions/46392415/fetch-value-of-a-field-from-one-entity-to-second-entity-based-on-the-lookup-fiel