Database Objects

You need to create database objects before you start developing your application. These database objects are primarily used to store and organize the data that your application manipulates. These databases objects include tables, indexes, views, sequences and synonyms. When creating some database objects, you need to specify a datatype for the data that is used by the object. When you create a table, you must specify a datatype for each of its columns. A datatype associates a fixed set of properties with the values that can be used in a column, or in an argument of a procedure or function. Each column value and constant in a SQL statement has a datatype, which is associated with a specific storage format, constraints, and a valid range of values. The most common data-types are character, numeric, and date.

Overview of Managing Objects

You need to create tables, indexes, and possibly other database objects in a schema before you start developing your application. A schema is a collection of database objects. A schema is owned by a database user and has the same name as that user, such as the HR schema. Schema objects are logical structures created by users. Objects

can define areas of the database to hold data, such as tables, or can consist of just a definition, such as views.

Tables are the basic database objects and contain all the user data. When creating a table, it is important that you define that data that you want to store in the table. You need to specify the datatype of the data and any restrictions on the range of values.

Database Objects for Your Application

Some object types have many more management options than others, but most have a number of similarities. Every object in the database belongs to just one schema and has a unique name within that schema. Therefore, when you create an object, you must ensure it is in the schema where you intend to store it. Generally, you place all of the

objects that belong to a single application in the same schema. A database object name must abide by certain rules. For example, object names cannot be longer than 30 bytes and must begin with a letter. If you attempt to create an object with a name that violates any of these rules, then Oracle Database XE raises an error.