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How to Simulate an SSRS Lookup in Telerik Reporting

Updated on Aug 28, 2026

Environment

Version	Product	Author
20.2.26.812	Telerik Reporting	Desislava Yordanova

Description

SQL Server Reporting Services (SSRS) provides the Lookup function for matching a value from the current dataset with a value in another dataset and returning a related value. Its syntax is:

text

=Lookup(source_expression, destination_expression, result_expression, dataset)

Telerik Reporting does not provide a built-in Lookup or LookupSet expression. The Fields global object reads fields from the current data scope, and the Exec function evaluates an expression in a parent data scope. Neither function performs a key-based lookup against an unrelated data source.

The recommended Telerik Reporting equivalent is to combine the related data before it reaches the report. When the sources are SQL tables, use a SQL JOIN and bind the report item to the resulting single data source.

Solution

Join the data in SQL

Suppose the report currently uses these datasets:

DatasetSales

ProductID	Quantity
1	10
2	5

DatasetProducts

ProductID	ProductName
1	Laptop
2	Mouse

Instead of using separate data sources and an SSRS-style lookup, create one query that joins the datasets:

sql

SELECT
    s.ProductID,
    s.Quantity,
    p.ProductName
FROM dbo.Sales AS s
LEFT JOIN dbo.Products AS p
    ON p.ProductID = s.ProductID;

Configure the Telerik Reporting SQL DataSource with this query. Bind the table to the resulting data source and use these expressions in the detail row:

text

=Fields.ProductID
=Fields.Quantity
=Fields.ProductName

The report displays the following result:

ProductID	Quantity	ProductName
1	10	Laptop
2	5	Mouse

A LEFT JOIN preserves rows from the primary dataset when no matching product exists. Use an INNER JOIN when rows without a match should be excluded.

Join tables from different databases on the same SQL Server

If the tables are in different databases on the same SQL Server instance, use three-part table names in the query:

sql

SELECT
    s.ProductID,
    s.Quantity,
    p.ProductName
FROM DatabaseA.dbo.Sales AS s
LEFT JOIN DatabaseB.dbo.Products AS p
    ON p.ProductID = s.ProductID;

The SQL login or database user used by the report must have permission to read both databases.

Combine the data in application code

If the sources cannot be joined in SQL, retrieve both sources in the application and create one collection of report rows containing the matched result. Bind the report item to that combined collection through an ObjectDataSource or by assigning the collection directly to the data item's DataSource property.

For example, the application-side result should expose properties equivalent to:

csharp

public sealed class SalesRow
{
    public int ProductID { get; set; }
    public int Quantity { get; set; }
    public string ProductName { get; set; }
}

The report then uses one data source and references the combined properties:

text

=Fields.ProductID
=Fields.Quantity
=Fields.ProductName

Perform the matching in application code before report processing. Do not attempt to retrieve the second source with Fields or Exec from a report expression.