A database object is any defined object in a database that is used to store or reference data. Some examples of database objects include tables, views, clusters, sequences, indexes, and synonyms. The table is this hour's focus because it is the primary and simplest form of data storage in a relational database.
A database object, within the context of Oracle, refers to a distinct, named structure that stores, organizes, and manages data within an Oracle Database. These objects are fundamental components of the Oracle Relational Database Management System (RDBMS) and provide a systematic approach for storing, retrieving, and manipulating data within the database. Oracle database objects can be broadly categorized into schema objects and non-schema objects.
Schema objects are objects that belong to a specific user's schema and are created and managed by that user. Some common schema objects include:
- Tables: These are the basic structure for storing data in an Oracle Database. A table consists of rows and columns, where each row represents a unique record, and each column represents an attribute of the data.
- Indexes: These are database objects that provide a fast, efficient, and organized way to access data in tables. Indexes are created on one or more columns of a table to facilitate quick data retrieval and improve query performance.
- Views: Views are virtual tables that display data from one or more base tables. They do not store data but instead provide an alternative way to access and manipulate data stored in the underlying tables.
- Sequences: These are database objects that generate unique, sequential numeric values. Sequences are often used to generate unique primary key values for tables.
- Stored Procedures and Functions: These are PL/SQL (Procedural Language for SQL) code blocks stored in the database, which can be called by applications to perform specific operations on data. Stored procedures do not return values, while functions return a single value.
- Triggers: Triggers are PL/SQL code blocks that automatically execute in response to specific events, such as data manipulation (INSERT, UPDATE, DELETE) or schema modifications. They can be used for enforcing data integrity constraints or performing custom actions.
- Synonyms: Synonyms are aliases for schema objects, providing an alternative name to reference a database object. They simplify SQL queries and can help provide security by hiding the underlying object's name and schema.
Non-schema objects, on the other hand, are objects that do not belong to a specific user's schema. These objects are typically shared across multiple schemas and are managed by the database administrator. Some common non-schema objects include:
- Tablespaces: These are logical storage units within an Oracle Database, used to allocate space for schema objects such as tables and indexes. Each tablespace consists of one or more datafiles, which store the actual data.
- Roles: Roles are collections of privileges that can be granted to users or other roles. They simplify the management of database access and security by grouping related privileges together.
- Profiles: Profiles are sets of resource limits and password policies assigned to users. They help enforce security and control resource usage within an Oracle Database.
Overall, database objects play a crucial role in the organization, management, and security of data within an Oracle Database environment. Understanding and working with these objects is an essential aspect of database administration and development.
