W. David Ashley - Access Db2 with Module-Based API Examples Using Python

Welcome to this introduction to Db2. Since you are here, you are likely looking for a place to get started with Db2. Our hope is that this book will be that first step you are looking for. This book is meant to be an introduction to the Db2 environment and to the Python interface. The first half of the book will cover Db2 at a level that should be of interest to both administrators and programmers. It will cover many aspects of Db2 that you will make use of in either of the two roles. The last half of the book will concentrate on using the Python programming language to interface to Db2. While mainly oriented to programmers, administrators will find it useful as well for some of their everyday tasks.

Db2 has a long history and is the first relational database implementation. It was first proposed by Edgar Frank Ted Codd in a paper titled A Relational Model of Data for Large Shared Data Banks in 1969 while working at the IBMs San Jose Research Laboratory in California. In the next four years, IBM researchers worked to create a system based on the principles described in Codds paper (called System R ). During this time, it became obvious that a new language was needed to interact with the new system. Codd wrote a new paper A Data Base Sublanguage Founded on Relational Calculus, which became the basis for the new language called DSL/Alpha . This quickly went through some name changes but eventually ended up being called SQL, short for Structured Query Language.

Eventually there was an effort in the 1970s to port DSL/Alpha to the 370 mainframe environment. It was renamed to Database 2 in 1982. The next year it was made available to the public with another name change, DB2. This was a limited release but was highly regarded by the customers that evaluated it. The customers actually pushed IBM to deliver DB2 to a wider set of customers. IBM was somewhat reluctant because they were trying to hold on to their IMS/DB market share. But eventually the customers won out, and DB2 began to spread to other platforms including OS/2, AIX/RS6000, and Windows.

The code bases for todays Db2 offerings share a common code base that makes porting the code to another hardware/software platform a relatively easy process. The SQL code base has been standardized so that it is the same across all platforms, making moving to another platform an easy task from a programming perspective.

There is also a current movement in programming applications with embedded SQL. These types of applications are very hard to port from one platform to another without major code modifications. Instead, IBM is moving (where possible) to an API that can be called to process SQL statements and make use of programming language variables for values to be added to the SQL statement. This is the methodology used for Python that we will explore later in this book.

In the past, Db2 was considered to be too large for most applications. But as personal computers have become a lot more powerful and then databases used by even a small number of people have become extremely large, Db2 has become more attractive in the management of this data. Also, the pricing model of Db2 on these platforms has become more competitive. So if you need the performance and the ability to manage large amounts of data, Db2 can be a very attractive product.