SharePoint Database Schema Change
Indicates any change made to the structure or object types associated with a SharePoint database or to the tables included in it. This includes any change to the SQL processing of data, such as triggers or adding new user-defined functions.
Real World Example
A developer wants to store additional data in the SharePoint database by adding new tables or new columns to an existing table.
You can perform a schema change by using a SQL script, by making the change manually, or by using code that has appropriate permissions to access the SharePoint databases. Always scrutinize any custom code or installation script for the possibility that it modifies the SharePoint database.
This type of customization is not supported.
Application of any schema change to the SharePoint database, except as part of a Microsoft-supplied service pack or hot fix, will make the SharePoint environment unsupportable. This type of change should never be applied.
Be sure to give special attention to any custom code you apply so that is does not introduce a database schema change into the environment.