Micro Focus NetExpress™

Database Access

Micro Focus®

Issue 2
October 1998

Micro Focus has made every effort to ensure that this manual is correct and accurate but reserves the right to make changes without notice at its sole discretion at any time.

The software described in this document is supplied under a license and may be used or copied only in accordance with the terms of such license, and in particular any warranty of fitness of Micro Focus software products for any particular purpose is expressly excluded and in no event will Micro Focus be liable for any consequential losses.

Micro Focus® is a registered trademark and Form Designer™, Micro Focus COBOL™ and NetExpress™ are trademarks of Micro Focus Limited.

Microsoft®, Windows®, and Windows for Workgroups®, are registered trademarks of Microsoft Corporation.

Visual Basic™ and Windows NT™ are trademarks of Microsoft Corporation

IBM® and DB2® are registered trademarks of International Business Machines Corporation.

UNIX® is a registered trademark of X/Open Company Limited.

Oracle® is a registered trademark of Oracle Corporation.

Sybase™ is a trademark of Sybase, Inc.

Copyright© 1987-1998 Micro Focus
All Rights Reserved.

Preface

This book describes how you can use NetExpress to create a COBOL application which uses embedded SQL to access a relational database. NetExpress provides:

• OpenESQL

  OpenESQL is an embedded SQL preprocessor which enables you to access ODBC-enabled data sources by embedding SQL statements within your COBOL program.

• DB2 ECM

  The DB2 External Checker Module (ECM) is a new type of integrated preprocessor provided with NetExpress and designed to work closely with the Micro Focus COBOL Compiler. The DB2 ECM converts embedded SQL statements into the appropriate calls to DB2 database services. It is intended for use with:

  • IBM Software Development Kit (SDK) for Windows 95/NT Version 2.1

  • IBM DB2 for Windows 95/NT Single User Version 2.1

  • IBM Distributed Database Connection Services (DDCS) for Windows NT Version 2.3

  • IBM DB2 Universal Database Version 5

  • IBM DB2 Connect Version 5

• COBSQL

  COBSQL is an integrated preprocessor designed to work with COBOL precompilers supplied by relational database vendors. It is intended for use with:

  • Oracle Pro*COBOL Version 1.8

  • Sybase Open Client Embedded SQL/COBOL Version 11.1

  You should use COBSQL if you are already using either of these precompilers with an earlier version of a Micro Focus COBOL product and want to migrate your application to NetExpress, or if you are creating applications that will be deployed on UNIX platforms. For any other type of embedded SQL development, we recommend that you use OpenESQL.

Notes:

• OpenESQL applications cannot be deployed on UNIX platforms.

• Use of COBSQL is only supported for standard procedural COBOL programs. You cannot use COBSQL with Object Oriented COBOL syntax (OO programs) or with nested programs.

Audience

This book is for NetExpress COBOL programmers who want to create or modify COBOL applications which access relational databases using embedded SQL.

It is assumed that you are already familiar with both SQL and, if you are using OpenESQL, ODBC. If you are using the DB2 ECM, it is assumed that you are familiar with DB2. If you are using COBSQL, it is assumed that you are familiar with the Oracle or Sybase database that you are accessing.

How to Use this Manual

Part One - Introduction

Chapter One, Introduction, gives a brief overview of embedded SQL and explains how you can build an embedded SQL application.

Chapter Two, Host Variables, describes host variables, host arrays, indicator variables and indicator arrays, and how they are used.

Chapter Three, Data Types, explains which data types are supported and how to map the data types used by a particular database to the correct COBOL picture clause.

Chapter Four, Cursors, details how to declare and open a cursor and how to use it to retrieve data.

Chapter Five, Data Structures, describes the SQLCA (SQL Communications Area) and the SQLDA (SQL Descriptor Area).

Chapter Six, Dynamic SQL, explains how to prepare and execute dynamic SQL.

Part Two - OpenESQL

Chapter Seven, OpenESQL, gives an overview of OpenESQL and how it works.

Chapter Eight, OpenESQL Assistant, is a tutorial which shows how you can use the OpenESQL Assistant to quickly and easily prototype SQL statements. Once you are happy with the SQL query you have created, the OpenESQL Assistant will insert the query into your program. It can also add required auxiliary code such as the CONNECT statement and host variable declarations.

Part Three - DB2

Chapter Nine, DB2, describes the DB2 ECM and how it is used.

Part Four - COBSQL

Chapter Ten, COBSQL, documents the COBSQL preprocessor explaining how it is used.

Notation

The following type styles and conventions have been used in this book:

• Text that you type is shown like this:

  cat script_name | more

  The italic text denotes a variable that you type as part of the command.

• Text in command lines or code examples that is optional is shown in square brackets. In the following example, the expression can specify that the column_name is like the pattern_value, or is not like the pattern_value, depending on the absence or presence of the optional word NOT:

  column_name [NOT] LIKE pattern_value

• Sections or paragraphs that apply only to a particular database or operating system are identified by a bold italic heading immediately preceding the paragraph it applies to. For example:

  OpenESQL
  This paragraph only applies to OpenESQL and not to DB2 or COBSQL.