System Tables Group

[This is preliminary documentation and subject to change.]

The tables of the system tables group track the tables and columns of the installation database.

• The _Tables table tracks all the tables in the database. This includes tables that you may have created for your own custom actions. Query this table to find out if a table exists.
• The _Columns table tracks every column in the installation database. Query this table to find out if a given column exists.
• The _Validation table. The _Validation table tracks the types and allowed ranges of every column in the database. The _Validation table is used during the database validation process to ensure that all columns are accounted for and have the correct values. This table is not shipped with the installer database.
• The _Sequence Table is used during the database validation process to ensure that all sequenced actions are in the correct order. The _Sequence table lists all the sequencing restrictions of all actions used in the installer database.
• The _InstallValidate Table is used with the _Sequence table during the validation process to ensure that the actions occur in the correct order.
• The _Required Table tracks the number of primary keys for all the tables in the database. It is only used during the database validation process.