Chapter4.Database Objects

Chapter 4. Database Objects

• Understanding data structures

• Managing database objects

• Creating database objects: data types, tables and table spaces, aliases and synonyms, constraints, views, materialized query tables, indexes, databases, storage groups, and sequence objects

• Database design and implementation

DB2 is a relational database that consists of one or more tables made up of rows and columns. The tables are created and accessed using the industry-standard Structured Query Language. Data in these tables is accessed via content, not location. This chapter looks at the structures in a DB2 subsystem and those that make up a DB2 database.

Many of these objects can be directly referenced from an SQL statement; therefore, it is important to understand their purpose. SQL is divided into three major categories.

1. DDL (Data Definition Language) is used to create, modify, or drop database objects.

2. DML (Data Manipulation Language) is used to select, insert, update, or delete database data (records).

3. DCL (Data Control Language) is used to provide data object access control.

As SQL has evolved, many new statements have been added to provide a more complete set of data access methods. The use of DDL to create database objects is discussed later in this chapter.