Relational Databases

A relational database management system stores and retrieves data in tabular format. A relational database consists of a collection of tables that store interrelated data.

• Database Tables
  In a relational database, all data is contained in tables, which are made up of rows and columns.
• Primary and Foreign Keys
  Primary and foreign keys enable each row in the database tables to be identified, and enable relationships between the tables to be defined. These keys define the relational structure of a database.
• Other Database Objects
  A relational database holds more than a set of related tables.
• Queries
  Basic query operations in a relational system are selection, projection, and join. The SELECT statement implements all of them.
• Other SQL Statements
  You can do more with SQL than just query. SQL includes statements that create tables, views, and other database objects. It also includes statements that modify tables (the insert and delete statements), and commands that perform many other database tasks discussed in this manual.
• System Tables
  Every database contains a set of system tables, which are special tables used by the system to manage data and the system. These tables are also sometimes called the data dictionary or the system catalog. In Sybase IQ they are stored in the catalog store.