02
Sat, Nov
2 New Articles

Building Python Applications That Work with Db2, Part 1

Programming - Other
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

At the most basic level, an application is a computer program that has been designed to perform a group of coordinated operations to solve a particular problem. Consequently, all applications are constructed around five basic elements.

Editor's Note: This article is excerpted from chapter 6 of QuickStart Guide to Db2 Development with Python, by Roger Sanders.

Those elements are:

  1. Input
  2. Logic (decision control)
  3. Memory (data storage and retrieval)
  4. Arithmetic operations (calculations or processing)
  5. Output

Input is defined as the way an application receives the information it needs to produce solutions for the problems it has been designed to solve. Once the appropriate input is received, logic takes over and controls what information (data) should be placed in or taken out of memory and what arithmetic operations should be performed on that information. (Because data placed into or taken out of memory is not persistent and can be lost if not physically stored somewhere else, applications often interact with the operating system to move data to and from simple character or byte-oriented files.) Finally, when the application has generated a solution to the problem it was designed to solve, it provides output in the form of an answer or specific action.

Applications that work with Db2 still contain these basic elements; the only real difference is the way in which persistent data is stored and retrieved, and in some cases, the way logic is exercised. File input/output (I/O) operations are replaced with SQL operations, and in some cases, decision control can be built directly into a Db2 database in the form of a trigger, stored procedure, or constraint. But, because of this difference, Python applications that use a Db2 database for persistent storage must perform three distinct tasks that are not required by more traditional applications:

  • Establish a connection to a Db2 server or database
  • Perform any transaction processing required (using SQL)
  • Terminate the connection when it is no longer needed

Additionally, Python applications that work with Db2 often perform other tasks like obtaining information about a specific database or retrieving Db2-specific error messages when a desired Db2 server or database operation fails.

Functionality Provided by the ibm_db and ibm_db_dbi Python Libraries

In Chapter 4, “Python and Db2,” we saw that there are two Python libraries that are used primarily to build Python applications that interact with Db2 servers and databases: the ibm_db library and the ibm_db_dbi library.

And, in Chapter 3, “The Db2 Call Level Interface,” we learned that many of the APIs found in the ibm_db library are similar to those found in the Db2 CLI driver. Table 6.1 shows the APIs available with this library, along with their purpose.

Building Python Applications That Work with Db2, Part 1 - Table 1

Because the ibm_db_dbi library adheres to the PEP 249 — Python Database API Specification v2.0, it contains only one API: the ibm_db_ dbi.connect() API. Once executed, attributes and methods associated with the Connection object this API returns can be used to perform basic operations against the connected Db2 server or database.

Table 6.2 provides Information about the ibm_db_dbi.connect() API, along with a list of the object attributes and methods that are available with the ibm_db_dbi library.

Building Python Applications That Work with Db2, Part 1 - Table 2

Building Python Applications That Work with Db2, Part 1 - Note 1

Special Objects Used by Db2-Python Applications

Db2 CLI/ODBC applications rely on special data storage areas to interact with Db2 servers and databases—these storage areas are identified by unique handles, which are simply pointer variables that refer to data objects controlled by Db2 CLI or the ODBC Driver Manager. Use of these storage areas frees Db2 CLI/ODBC applications from having to allocate and manage global variables and Db2-specific data structures.

Because the Db2 CLI driver serves as the foundation for the ibm_db and ibm_db_dbi Python libraries, both of these libraries rely on similar special data objects to interact with Db2 servers and databases. With the ibm_db library, IBM_DBConnection and IBM_DBStatement objects are used; with the ibm_db_dbi library, Connection and Cursor objects are used instead. As the name implies, IBM_DBConnection and Connection objects are used to store information about a Db2 server or database connection, such as:

  • The current state of the connection being managed
  • The current value of each connection attribute available
  • Diagnostic information about the connection the object refers to

On the other hand, IBM_DBStatement and Cursor objects are used to store specific information about a single SQL statement (and its associated cursor, if any), such as:

  • The current value of each SQL statement attribute available
  • The addresses of application variables that have been bound to (associated with) parameter markers coded in the SQL statement the object refers to
  • Diagnostic information about the SQL statement the object refers to

Stay tuned for Part 2, coming soon in an upcoming issue of MC TNT. Can't wait?  You can pick up Roger Sander's book, QuickStart Guide to Db2 Development with Python, at the MC Press Bookstore Today! 

 

Roger Sanders

Roger E. Sanders is a Principal Sales Enablement & Skills Content Specialist at IBM. He has worked with Db2 (formerly DB2 for Linux, UNIX, and Windows) since it was first introduced on the IBM PC (1991) and is the author of 26 books on relational database technology (25 on Db2; one on ODBC). For 10 years he authored the “Distributed DBA” column in IBM Data Magazine, and he has written articles for publications like Certification Magazine, Database Trends and Applications, and IDUG Solutions Journal (the official magazine of the International Db2 User's Group), as well as tutorials and articles for IBM's developerWorks website. In 2019, he edited the manuscript and prepared illustrations for the book “Artificial Intelligence, Evolution and Revolution” by Steven Astorino, Mark Simmonds, and Dr. Jean-Francois Puget.

From 2008 to 2015, Roger was recognized as an IBM Champion for his contributions to the IBM Data Management community; in 2012 he was recognized as an IBM developerWorks Master Author, Level 2 (for his contributions to the IBM developerWorks community); and, in 2021 he was recognized as an IBM Redbooks Platinum Author. He lives in Fuquay Varina, North Carolina.


MC Press books written by Roger E. Sanders available now on the MC Press Bookstore.

QuickStart Guide to Db2 Development with Python QuickStart Guide to Db2 Development with Python
Discover how Python, SQL, and Db2 can successfully be used with each other.
List Price $9.95

Now On Sale

DB2 10.5 Fundamentals for LUW (Exam 615) DB2 10.5 Fundamentals for LUW (Exam 615)
Don't even think about attempting to take the DB2 Fundamentals exam without this indispensable study guide.
List Price $79.95

Now On Sale

DB2 10.1 Fundamentals (Exam 610) DB2 10.1 Fundamentals (Exam 610)
Let one of the world's leading DB2 authors and a participant in the exam development help you succeed.
List Price $79.95

Now On Sale

Artificial Intelligence: Evolution and Revolution Artificial Intelligence: Evolution and Revolution
Operational AI has become available to the masses, setting the wheels in motion for a worldwide AI revolution that has never been seen before.
List Price $16.95

Now On Sale

DB2 10.5 DBA for LUW Upgrade from DB2 10.1: Certification Study Notes DB2 10.5 DBA for LUW Upgrade from DB2 10.1: Certification Study Notes
Here's everything you need to know to take and pass Exam 311, complete with a practice exam and study key.
List Price $21.95

Now On Sale

From Idea to Print From Idea to Print
Here's everything you need to know to turn your technical knowledge and expertise into a published article or book.
List Price $49.95

Now On Sale

DB2 9 Fundamentals (Exam 730) DB2 9 Fundamentals (Exam 730)
Use this review before taking the test to prove you've mastered the basics of DB2 9.
List Price $59.95

Now On Sale

DB2 9 for Linux, UNIX, and Windows Database Administration (Exam 731) DB2 9 for Linux, UNIX, and Windows Database Administration (Exam 731)
Use this indispensable study guide to prepare to take, and pass, Exam 731.
List Price $64.95

Now On Sale

DB2 9.7 for Linux, UNIX, and Windows Database Administration (Exam 541) DB2 9.7 for Linux, UNIX, and Windows Database Administration (Exam 541)
Get ready to take the DB2 9.7 certification exam with this handy study guide.
List Price $21.95

Now On Sale

DB2 9 for Linux, UNIX, and Windows Advanced Database Administration (Exam 734) DB2 9 for Linux, UNIX, and Windows Advanced Database Administration (Exam 734)
Review all exam topics and take the included practice test to be sure you're ready on testing day.
List Price $64.95

Now On Sale

DB2 9 for Linux, UNIX, and Windows Database Administration Upgrade (Exam 736) DB2 9 for Linux, UNIX, and Windows Database Administration Upgrade (Exam 736)
Prep for success with the master of DB2 certification study guides!
List Price $34.95

Now On Sale

Data Fabric: An Intelligent Data Architecture for AI Data Fabric: An Intelligent Data Architecture for AI
This book explains the concepts and values that a data fabric approach can deliver to both technical and business communities.
List Price $19.95

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: