Using the Guide Database Schema

To investigate and print out the details of the Guide database schema, including field descriptions, field sizes, and referential integrity rules, you can make a copy of the empty database installed by the broadcast client installation program. You can then examine the copy using Microsoft® Access, as described in the following procedure.

To examine the Guide database schema in detail

1. Open Microsoft® Windows Explorer.
2. Open the folder for Microsoft® WebTV® for Windows. This folder resides within the folder where the broadcast client software resides on your computer.
3. Select the two database files, Tss.mdb and Tss.mdw.
4. Copy these files to a different folder convenient to your development project.
5. Use Access to open these files, and explore and print out the database structure as explained in the Access documentation.

For improved performance and ease of navigation, many of the tables in the Guide database schema are referentially linked with automatically generated counters. The referential integrity of these counter fields is guaranteed by:

• The Microsoft® Jet database engine.
• The schema structure.
• The behavior of the database loader.

You can use these automatically generated identifier (ID) fields in queries and code that navigate among the tables. However, you should never store these identifier fields externally to the database, because their values are subject to ongoing change when the database loaders add and delete records as part of updating the database. If an application must save an external reference to an item in the database, it must use one of the key fields flagged as external to do so.