Summary

Data sources provide the report with a connection to the data. Data sets use the data source along with a query of some kind to produce a resultset that the rendering engine takes and uses to process the report.

Data sources can be either specific to a report or shared among many reports . SSRS can natively hook into SQL Server, Analysis Services, Integration Services, and Oracle. A number of other providers are supported through ADO.NET, and if a provider is not available, one can be custom developed. It is helpful from an administration point of view to use a shared data source whenever possible. An exception to this is when a data source needs specific credentials or elevated security.

Visual Studio offers two query designersthe Graphical Query Designer and the Generic Query Designer. SSRS leaves the processing of the query to the data source. After the data source is finished processing the data, it generates a data set, which is a collection of fields inside of rows. Calculated fields can be added to the data set at design time to augment the returned results. Filters can also be applied to the resulting data sets. Both filters and fields are applied on a row-by-row basis and, if not used carefully , can lead to performance problems.

Parameters can either be static or bound to data sets. The value of certain parameters can also be passed in as input to a query. The output of that query can be used as the list of values for a parameter, in effect creating a dependency between parameters and data sets. This dependency can be used in many different ways to affect the data used in the final data set processed .