DAX function

LOOKUPVALUE — DAX function reference

Look up a value with no relationship.

Syntax

dax

LOOKUPVALUE(<result_columnName>, <search_columnName1>, <search_value1> [, <search_columnName2>, <search_value2>, …], [<alternateResult>])

dax

LOOKUPVALUE(Rate[USD], Rate[Date], Sales[Date])

→ A value

dax

LOOKUPVALUE(Rate[USD], Rate[CurrencyCode], Sales[CurrencyCode], Rate[Date], Sales[Date], 1)

→ Multi-column lookup — matches on both currency and date, defaulting to 1 if not found

dax

LOOKUPVALUE(Employee[ManagerName], Employee[EmployeeID], Sales[SalesRepID])

→ Pulls a value with no physical relationship between Sales and Employee

LOOKUPVALUE requires the search values to identify at most one matching row — if more than one row matches, it returns an error rather than the first match.
It's a row-by-row scan with no relationship/index to help it, so it's noticeably slower than RELATED on large tables — use it only when there's genuinely no relationship to model, not as a substitute for a real one.

From Relationships