If you edit a channel for which a database is specified as the source component, you must update the database tables if you:

• Change any of the table definitions in the VMD file that defines the tables for your database, or
• Add a new message definition to the VMD file.

If you edit a channel for which a database is specified as the destination component, you must update the database tables if you change any of the table definitions in the VMD file that defines the tables for the database.

There are two ways to update database tables:

• Re-export the Data Tables: This will drop the existing data tables and replace them with new ones. Any data in the existing tables is lost, which may lead to undesirable results. (See Exporting the Database Tables for more details on re-exporting the data tables.)

• Modify the existing tables to match the table definitions in the VMD file: Any columns that you add to a table definition in the VMD file must be manually added to the corresponding database table. This requires more effort, but is potentially safer.