Question : DLookup with multiple criteria

Experts,

I am having a problem contructing a DLookup function in a query that looks for a value in a table.

Table: tblProduction
Field Name1: ProductName (numeric)
Field Name2: Year (numeric)
Field Name3: OpQty (numeric)

Query Name: qryInventoryInsAndOuts
Query Field1: ProductName (numeric)
Query Field2: Year (numeric)

OpQty is actually ending inventory which would also be beginning inventory for the next year. I want to be able to show beginning inventory in the query using a DLookup function.

What I want to do:
Beginning Inv: Lookup OpQty in tblProduction where ProductName in the table = ProductName in the query AND Year in the table = Year MINUS 1 in the query.

This function does not work, but should be pretty close:
Beginning Inv: DLookUp("[OPQty]","tblProduction","[Year] = [Year] and [ProductName]=[ProductName]")

Thanks, Dale

Answer : DLookup with multiple criteria

try this

SELECT ProductName, [Year], DLookUp("[OPQty]","tblProduction","[Year] = " & [Year]-1 & " AND [ProductName] =" & [ProductName]) AS [Beginning Inv]
FROM tblProduction