Implementing Practical DB2 Applications

Transcription

1 Anthony S. Rudd Implementing Practical DB2 Applications With 69 Figures, Springer

2 Antho ny S. Rudd. MS(Hons) OateveG Paumgartnerstrasse Nuremberg. GERMANY ISBN-I3: Dar: / e-isbn-i3: British Library Cataloguing in Publication Data Rudd, Anthony S. Implementing practical OB2 applications. - 2nd ed. 1.0B2 (Computer program) 2.0atabase management - Computer progralt\$ I.Title 005.1'56'5 ISBN-I3: Library of Congrus Cataloging-in-Publ ieat ion Data A catalog record for this book is available from th e Library of Congress Apart from any fair dealing fo r the purposes of research or private study, or criticism or review, as pe rmitted under th e Copyright, Designs and Pate nts Act 1988, this publication may only be reproduced, stored o r transmiued, in any fo rm or by any means, with Ihe prior pe rmiuion in writing of the publishers, or in the cue of reprographic reproduction in accordance wilh the terlt\$ of licences iuued by th e Copyright lice nsing Agency. Enquiries co nce rning reproduction outside those te r lt\$ should be sent to th e pub/is hers. e Springer-Verlag london l imited 1996 The use ofregisthed names, Irademarb etc. in th is publication does not imply, even in th e abunce of a specific statement, that such names I re exempt from Ihe releyant la ws and regulations Ind therefore free for general use. The publisher makes no representation, txpreu or implied, with regard 10 the accu racy oftht information contained in this book and Clnnot accept any legal responsibility or liability fo r any erron or omiuions that may be made. Typeuning: camna ready by author Printed on acid free paper

3 Preface The title of this book "IMPLEMENTING DB2 APPLICATIONS' reveals the purpose I had in writing it: a concise, complete, source of information necessary for the development and implication of applications using IBM'S DB2 relational database package in the MVS environmenl. When I started wriling DB2 applications I was quite literally overwhelmed by the physical amount of literature available. And usually all of this literature was necessary as reference for the writing of an application, because the required infonnatian was distributed amongst the manuals. With this book I have tried to separate out that information necessary to put an application together. This book is hopefully more than a mere reference; it contains tips and notes I and my colleagues found out the hard way. I have tried to present this practical information in such a form that it is easy to find and use. I hope this will enable readers to spend more productive time developing applications, rather than trying to find out why something works in a particular way. Good though the IBM manuals are, they suffer from two drawbacks: they have now attained a s ize (and weight) that they are unwieldy to use; reference manuals offer limited scope to explain background information or critique, where it might be required. And who should read this book? Both beginners and expens. Beginners are lead through the steps required to put DB2 applications together; complete worked examples, large enough to be practical but devoid of superfluous

4 vi PREFACE detail, enable the DB2 novice to see what is necessary to implement a simple application. Experts have a compact reference for those features necessary to write a DB2 application. In particular, the mechanics of preparing and testing a DB2 application program. What this book is not? This is not a book about SQL; there have been enough books published already on this subject. This book does not go into the details of writing SQL statements, although it is sufficiently detailed to serve as a basic reference, rather it describes how the various components fit together. Similarly, it does not treat the subjects of distributed applications and optimisation. Also, it does not discuss the internal processing and optimisation aspects of DB2 systems. These are all specialised topics, a discussion of which would conflict with the aim of having a compact book. At this point I would like to thank Elke Berger for her help and suggestions for improvements.

5 Table of Contents Preface v I. Introduction 1.1 DATABASE2 (OB2) environment... I I.2 DBl data objects I. 3 Access to DB2 tables UseofSQL Use of SQL from applications Applicalion Design 2.1 Application design......,., Application considerations Dialogue or batch? Command procedure Static or dynamic SQL? Changes to the database... to Authorisation considerations Which product to use QMF Facilities 3. 1 Introduction t QMF objects QMFquery QMF data QMF form QMF report QMF procedure

6 viii TABLE OF CONTENTS QMF profile QMF chart QMF invocation QMF command facilities Transfer of QMF items to/from host system Administration of QMF objects Invoke host system component Invocation of QMF QMF files Sample CLIST for invocation of QMF QMF callable interface The DSQCOMM communications area Callable interface invocation syntax START command Examples QMF command interface QMF status Passing parameters to a QMF command QMF Commands 4.1 Introduction Commands DISPLAY - Display an object END - End current operation ERASE - Remove object from database EX IT - Terminate QMF session EXPORT - Transfer object to external dataset HELP - Display help information IMPORT - Impon object into the QMF environment INTERACT - Provide interactive suppon ISPF - Invoke ISPF/PDF panel LIST - Display list of QMF objects MESSAGE - Display message PRINT - Print content of object QMF - Execute explicit QMF command RESET - Clear object RESET QUERY - Clear query object RESET GLOBAL - Clear global variable RUN - Execute object SAVE - Save contents of work area SAVE DATA - Save contents of data area SAVE PROF I LE - Save profile SET (PROFILE) - Set profile SET GLOBAL - Set global variable STATE - Return QMF status TSO - Invoke TSO command Example External QMF data QMF external data format IXF data... 58

7 TABLE OF CONTENTS ix QMF external data QMF data format.. QMF repon data Program Environment 5.1 Introduction lcl procedures PU I preprocessor OB2 precompiler Compile Pre linkedit Linkedit Bind Example OB21 (OB2 Interactive) DB2 program Invocation 6.1 Introduction Commands penaining to OB DSN - Invoke OBI session OS NH - Prepare program in foreground OB2 subcommands BIND PACKAGE - Build application package BIND PLAN' Build application plan OCLGEN -Table declaration generator END - Terminate OB2 session FREE - Free application plan REBUO - Rebind application plan RUN - Invoke OB2 program spun -SQL Processor Using File Input DB2! (OATABAS E2 Interactive) Invoke SPUfl Invoke OCLGEN Perform OB2 Program Preparation Perform OB2 Precompile Perform OB2 Bind function Run an SQL program Set OB21 global default parameters Invoke program independent of OBI (CAF interface) CLOSE function CONNECT function DISCONNECT function OPEN function TRANSLATE function CAF interface program Issuing SQL statements from within a program 7. 1 Introduction SQL status DSNTIAR subroutine

8 x TABLE OF CONTENTS Program host variables PU I hosl variables COBOL host variables Assembler hosi variables CI370 host variables Indicator variables Use of SQL from programs Static SQL Static SQL select with a fixed number of columns Dynamic SQL Dynamic SQL wilh a variable number of columns Embedded SQL Statements Introduction Statements BEGIN DECLARE - Start declaration of hosl variables CLOSE - Close cursor COM/'IIT - Make outstanding database changes permanent DECLARE CURSOR - Define cursor DECLARE STATEMENT - Define SQL statement name DECLARE TABLE - Define table structure DELETE - Delete rows DESCRIBE - Obtain information aoom a prepared statement END DECLARE - Terminate declarations EXECUTE - Execute a prepared statement EXECUTE IMMEDIATE - Prepare and execute an executable SQL statement E)(PLA t N -Obtain processing statistics FETCH - Position cursor to next row INCLUDE - Include definitions INSERT - Insert rows LOCK TABLE - Set lock OPEN - Create results table for select PREPARE - Prepare SQL statement ROLLBACK - Revoke outstanding database changes SelECT INTO - Produce single-row results table UPDATE - Update database rows WHENEVER - Define exception processing Transaction Processing 9.1 Introduction SQL transaction concepts Consistency Concurrency Testing Introduction DB2 testing tools Testing of programs using DB2 (SQL) facilities Testing using the CAF interface

9 TABLE OF CONTENTS xi O.J Testing by creating the DB2 environment Testing using ISPFfPDF Dialog Test CommitfRollback in the testing environment Summary Worked Example 11. I Introduction Il.l Problem specification QMF solution Program solution Summary Appendix A. Syntax Notation Appendix B. SQL Control Areas Appendix C. Glossary Index