In Web, you can  configure one-to-many data link relationships on a layer extension. A data link retrieves information from the field attributes in an external data source (e.g., the web, another business enterprise application, or a database on the network), and displays it alongside your Esri data. The data retrieval happens in the background, without any knowledge or action required on your user's behalf.

To perform a data link, you must have the following:

•Either a client-side workflow (ideal for gathering data from other systems via API calls) or a server-side workflow (ideal for gathering data from local ODBC-connected data, e.g., Microsoft SQL Server).

•A familiarity with the external data source and its field attributes.

See Create a Data Link.