Automatic Database Table Creation

If you deploy an EJB 2.0 or 3.0 CMP project to OC4J configured to use TopLink as the persistence manager, then you can configure OC4J to automatically create (and, optionally, delete) database tables for your persistent objects.

You can configure automatic database table creation at one of three levels as Table 6-2 shows. You can override the system level configuration at the application level and you can override system and application configuration at the EJB module level.

Table 6-2 Configuring Automatic Table Generation

Level	Configuration File	Setting	Values
System (global)	<OC4J_HOME>/config/application.xml	autocreate-tables	TrueFoot 1  or False
		autodelete-tables	True or FalseFootref 1
Application (EAR)	orion-application.xml	autocreate-tables	TrueFootref 1 or False
		autodelete-tables	True or FalseFootref 1
EJB Module (JAR)	orion-ejb-jar.xml	pm-properties sub-element default-mapping attribute db-table-genFoot 2	Create, DropAndCreate, or UseExistingFoot 3

^Footnote 1 Default.

^Footnote 2 For more information, see "Configuring default-mapping Properties".

^Footnote 3 See Table 6-3.

If you configure automatic table generation at the EJB module level, the value you assign to the db-table-gen attribute corresponds to the autocreate-tables and autodelete-tables settings as Table 6-3 shows.

Table 6-3 Equivalent Settings for db-table-gen

db-table-gen Setting	autocreate-tables Setting	autodelete-tables Setting
Create	True	False
DropAndCreate	True	True
UseExisting	False	NA

You can use this feature in conjunction with default mapping (see "Default Mapping in EJB 2.0 or 3.0 CMP Projects Using OC4J at Run Time").