Data Lookup
Guide for creating ServiceNow Data Lookup definitions (dl_definition) using the Fluent API. A Data Lookup connects a source table to a configurable matcher table and defines which source fields are used to find a matching row and which values are copied back to the source record. In simple terms form field change, record insert, and record update. If you find yourself reaching for a Business Rule (for insert/update) plus a Client Script (for onChange) to implement the same deterministic field-population logic, use Data Lookup instead.