Zusammenfassung der Ressource
Object-relational database
- Features
- Advantages
- Ease of use
- Flexibility
- Precision
- Security
- Data Independence
- Data Manipulation Language
- Disadvantages
- machine performance
- Schema Changes
- Language Dependence
- Lack of Ad-Hoc Queries
- object types
- model real-world entities
- Object Columns
- An object column is a column in a table that is defined using an object type.
- Object Tables
- object table is a table in which each row contains one object of a given object type.
- NULL
- atomic NULL
- object can be atomically NULL
- cannot be updated
- NULL attributes
- object can have attributes that are NULL
- Updates on its individual attributes
- Must use cascade clause
- collection types
- VARRAY
- variable sized array which has ordered set of data elements of the same type.
- Nested tables
- Tables are ordered set of elements of the same data type