PPT Slide
Other Data Definition Features
- ref is for object id column
- Unique, user-generated (on insert)
- scope clause for reference columns
- Provides critical information to the query optimizer
- not null constraints
- Definable at any level of a table hierarchy
- Enforced for indicated table and its subtables
- unique constraints
- Root level (and columns) only
- create index for physical schema
- Unique or non-unique index on root table
- Non-unique index on subtable