Below example will show how to use lookup function in SSRS.
I have created two dataset named DST_ProductDetail and
DST_ProductName.
DST_ProductDetail
select ProductKey,UnitPrice,SalesAmount,TaxAmt from FactInternetSales
DST_ProductName
select ProductKey,EnglishProductName from DimProduct
We need to display product name with
respective detail in the table. For that need to use lookup function. Here
DST_ProductName will be used as reference dataset.
Design the table
Click on the expression of the Product
Name column. Enter the below code
=Lookup(Fields!ProductKey.Value,Fields!ProductKey.Value,Fields!EnglishProductName.Value,
"DST_ProductName")
Now Run the report. You can see all
the Product Name will be appeared in the table.