Oracle and DB2, Comparison and Compatibility/Storage Model/Tables

= Overview =

Tables are the most easily recognized structure in relational databases. All relational databases store user information in tables, and it’s how we visualize the data - tables contain rows and columns.

In addition to tables that are stored on disk, there are ‘virtual tables’. Virtual Tables are called views. This descriptive term describes exactly what they are, it is a structure that is made up of selected columns from one or more tables. Views are a useful construct for simplifying data access – for example, if a user is not experienced in SQL, a view can be created for them. This is also useful for security purposes; certain table data can be made accessible through views only to selected users. Complex data structures can be constructed with views and this approach can hide this complexity from users.