Maintaining Application Schema Metadata

What Is Schema Metadata?

Schema metadata about tables includes:

The application module in which a table belongs
Data about table triggers, such as whether a primary key is generated, whether inserts or updates are allowed, and so on
Data about AlphaKeys (or Next Keys), which are system-generated values used as keys
Data about user extended table (UET) inheritance
Data about views generated for multi-site tables
Data about application-specific table extensions, such as ERDBGW population for APS

The system refers to this metadata when generating table triggers.

NOTE: When you create a new table, first try generating and testing table triggers without adding your table to the metadata. If it works the way you want, do not add it to the metadata. Otherwise, refer to this section and the related topics to determine how to add metadata to adjust the generation.

Defining Metadata

After you create a custom table or a custom column on a standard table, define any needed metadata as follows:

Use the Application Schema Modules Metadata form to define any custom modules.
Use the Application Schema Tables Metadata form to:
- Assign custom tables to the appropriate module.
- For backward compatibility with existing multi-site tables, assign a viewname. The viewname should match the former table name. For example, a table formerly named item which is now item_mst would have a view named item. Specify a column name that contains the site value. The combination of view name and site value is used to create a view over the table.
- Specify information about insert and update triggers on the table.
- When UETs are added to the currently selected table, specify any other tables to which the UETs should be applied.
If a table has an AlphaKey (you want to generate Next Keys for a column in the specified table), use the Application Schema Columns Metadata form to define this.
If using this application with APS and you want to populate ERDBGW for APS for the new table, define the appropriate extensions in the Application Schema Tables Metadata Extensions form.

If you later remove a custom table or column from the application database schema, you must also remove the corresponding row from the application schema metadata, if that row exists.

Generating Triggers

To generate triggers using the metadata you defined, use the Trigger Management form, specifying the tables where you changed metadata.

Triggers require generation after you:

Add columns to standard tables.
Add custom tables, if you want standard trigger functionality.
Impact the schema for User Extended Tables with the UET Impact Schema form. (This generates triggers automatically and creates views for multi-site tables.)
Upgrade databases where the schema has changed. (This generates triggers automatically.)
Run the Database Migration utility. (This generates triggers automatically.)

Building and Running Scripts

You can dump the metadata into SQL scripts which can then be loaded into other application databases, for example at other sites where the same table/column changes are being made. Follow these steps:

In one site, define the metadata as described above.
Use the Generate Application Schema Metadata Scripts form to create the following scripts, as needed:
- Module metadata, which was defined in the Application Schema Modules Metadata form
- Tables metadata, which was defined in the Application Schem Tables Metadata form
- Column (Next Keys) metadata, which was defined in the Application Schema Columns Metadata form.
If using this application with APS, use the Generate Application Schema Metadata Extensions Script form to create a SQL script with table-based attribute extensions metadata.
Load the SQL script(s) into other sites (application databases), which must also contain any applicable new or modified schema elements.
At these other sites, use the Trigger Management form to generate triggers for specified tables.

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