To employ the above-demonstrated feature of SPRadGrid's you need to make use of the designer that comes with the new version of the TelerikSPRadGrid web part. It is loaded through the WebPart's menu option SPRadGrid Designer:
The Web Part designer is very similar in logic and organization to RadGrid's Visual Studio designer. It provides the option to construct the general hierarchical structure of the grid adding/deleting detail table views, set some important properties of the latter (such as Paging, Filtering, Sorting and others) and specify the data source to which the table views should be bound:
To start constructing with the Web Part designer, first select a table view from the upper-left tree view. The bottom right one is now loaded with two options to select from: General Settings and DataBinding. Clicking upon the General Settings node will allow you to set the most important properties for the selected table view:
Selecting the DataBinding option from the bottom left tree view will load the SQL and SP lists explorer into the top right pane.
When an instance of an SQL server is chosen as the data source for a given table view, the user will be prompted to provide his/her credentials before being able to browse the server's databases and tables:
No log-in credentials will be required when binding to SP Lists as the current user's SP account is taken into consideration.
If an SQL table or SP List is clicked upon, the designer will remember it as the underlying data-source of the selected table-view. To change the data-source just select a different table/list.
Upon having chosen an SQL table the designer automatically loads its columns into the bottom right pane for you to pick the ones to be displayed in the grid. If the currently selected grid table view is a detail one you will be given the additional option to specify a master-child relation.
No columns are selected for the SP lists but instead the user is prompted to pick the SP View which the grid table view should be bound to.
The SPRadGrid Designer does not preclude the use of the Web Part's Tool Part and it has been left as an additional option if you need to bind the grid control to just a single SharePoint list without opening the designer. What's new in the Tool Part is that the Grid Settings Panel now features a Binding Mode property that tells the Web Part what type of data-source should be used. The relevant Binding Mode options are respectively: SQL, SPList and Single SP List.