Record and table handling

 Course Length: 10 days  Topics Agenda  Getting Started - installing and configuring RDz - and the course materials, and using Eclipse to edit COBOL  COBOL General Language Rules  B

IBM Software Group

© 2006 IBM Corporation

Enterprise COBOL Education Using Rational Developer for System Z

Intermediate COBOL Record and Table Handling Patterns

Jon Sayles, IBM Software Group, Rational EcoSystems Team

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 © Copyright IBM Corporation 2007,2008 All rights reserved

 The information contained in these materials is provided for informational purposes only, and is provided AS IS without warranty of any kind, express or implied IBM shall not be responsible for any damages arising out of the use of, or otherwise

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Course Contributing Authors

 Thanks to the following individuals, for assisting with this course:

 David Myers/IBM

Purpose of This Document

 Course Name: COBOL Foundation Training - with RDz

 Course Description: Learn the COBOL language, RDz and learn z/OS terms, concepts and development skills in this course

 Pre-requisites: Some experience in a 3rd or 4th Generation Language is expected SQL is also recommended.

 Course Length: 10 days

 Topics (Agenda)

 Getting Started - installing and configuring RDz - and the course materials, and using Eclipse to edit COBOL

 COBOL General Language Rules

 Basic COBOL Statements

 Additional record and table handling

 Debugging Programs - Note: Deep dive on using RDz for common COBOL programming errors (001, 0C4, 0C7, infinite loops, fall-thru, etc.)

 Input/Output and Report Writing Patterns

 COBOL Subprograms and the Linkage Section

 Structured Programming Concepts, professional COBOL development practices and Coding Patterns

 Advanced Character Manipulation, COBOL Intrinsic Functions, Date and Time coding patterns, and Language Environment calls

 OS/390 Concepts and JCL - Compile/Link & Run Procs on the mainframe

 Indexed file Coding Patterns

 Sort/Merge, Sequential File Match/Merge and Master File Update Coding Patterns

 Accessing DB2 Data and DB2 Stored Procedures

 COBOL in the Real World:

– CICS - lecture only – IMS (DL/I and TM) - ditto – Batch processing - ditto – Java calling COBOL – COBOL and XML Statements – SOA and COBOL - creating and calling Web Services – Web 2.0 using Rich UI

 This course assumes that the student has the basic knowledge of IS

technologies, data processing, software and have programmed for at least two or more years in a language such as: Java, VB, RPG, PL/1, Pascal, or some 4th Generation Language or tool

 Knowledge of SQL (Structured Query Language) for database access is

assumed as well.

 Basic PC and mouse-driven development skills is also assumed.

 Finally, it is assumed that you have been following along in this course, and have successfully completed the learning modules in sequence.

 Or have the equivalent COBOL background obtained through some other form of COBOL study or on-the-job work.

Unit

 Additional Record Concepts Additional Record Concepts

 COBOL Tables – Definition and Language Concepts

 Multi-Dimension COBOL Tables

 Variable Length COBOL Tables

 Searching COBOL Tables

 Processing COBOL Tables With Intrinsic Functions

Topics:

Additional Record and COBOL Table Handling Facilities

COBOL Records – Review

 COBOL records are hierarchical structures that allow you to organize ("model")

sophisticated real-world complex data

 Records have a 01 level number definition

 Coded beginning in the "A" margin

 Typically with no PIC clause

 01 Employee-Data.

 And records continue with one-to-many elementary items – some of which may be

"group" data items (with no PIC clause)

 Here's an example shown in COBOL and graphically (with data)

REDEFINED Fields

 In many of the COBOL applications you will work in, you will encounter situations where fields in records are REDEFINED (the actual COBOL keyword is

REDEFINES) – with different PIC clauses.

 REDEFINES means that the same area of storage in the DATA DIVISION can be referenced in two or different ways

A 3 4 T 9 7 b b b b b b b b b b b b b b b b b b b b b b b b b Postal-Box Filler

Defining and Using REDEFINED Fields

 Language Rules – How to declare or REDEFINE a field:

 You redefine a field:

 At the same level number

 The level numbers can not be: 88, 66, 01 (in the FILE SECTION) – but you can REDEFINE an 01 record in WORKING-STORAGE

 Immediately following the field –with no higher level numbers between (higher in the COBOL hierarchy)

 The data description entry for other-data-item cannot contain an OCCURS clause

 The redefining field should (does not have to, but should) have the same number of characters as the Redefined field

 You can have multiple redefinitions of the same field's character positions

 However, they must all refer to other-data-item, the data-name that originally defined the area

 The redefining entries cannot contain VALUE clauses except in condition-name entries

How to tell which field to reference:

(The redefining or the redefined)

 Typically your record will have a flag or some sort of indicator

variable that distinguishes the record types

 Usually this is one-byte "flag" – PIC X field that carries a value which describes the data that follows

 See the example on the right 

01 DATE-TABLE.

05 DATEVALS PIC X(30) VALUE "312831303130313130313031".

05 Month-Days REDEFINES DATEVALS PIC 9(2) OCCURS 12

REDEFINED Records

 In the WORKING-STORAGE SECTION (not in the FILE SECTION) you may redefine at the 01-record level

 This was common practice in older systems that were memory or storage-constrained.

 Typically you might have (at least) 3 different records read:

 Header-Rec: With Job run-date information, Company Name, etc.

 Detail-Rec: With the base information to be processed

 Note that within the detail record, you might very well find additional REDEFINE fields

 Trailer-Rec: With more balancing total amounts, etc

… Perform Detail Record Processing

Lab Assignment

From the course workshop documents, do the following labs:

1 Data Representation and assignment (MOVE statement) Lab

2 Open ended workshop

Unit

 Additional Record Concepts

 COBOL Tables – Definition and Language Concepts

 Multi-Dimension COBOL Tables

 Variable Length COBOL Tables

 Searching COBOL Tables

 Processing COBOL Tables With Intrinsic Functions

Topics:

Additional Record and COBOL Table Handling Facilities

Topic Objectives

By the end of this unit you should be able to:

 Describe the COBOL OCCURS clause and code a syntactically correct example

 Describe the differences between a subscript and table index

 Create COBOL one-dimension table, by redefining values in Working-Storage

 Initialize and load data in a COBOL table

 Refer to specific table row/field table occurrences in the Procedure Division

COBOL Tables – Overview

 Like most programming languages, COBOL can group variables of the same type

in internal program tables

 COBOL supports the following kinds of table structures:

1 Single COBOL field tables

2 Fixed-length Structure field tables – the most common format

3 Variable-length tables – where the number of table occurrences is not known until run-time

 From this example:

 Sample-Table-One is a group data item

 Table-Column is a group data item that is repeated three times

 You can conceptualize fields with an OCCURS clause as: OCCURS

– Rows Rows – if you're visualizing the data in storage vertically

 Table-Item-1 and Table-Item-2 are elementary data fields – that are

repeated three times, as they are child variables of Table-Column

Fixed-Length COBOL Structure Table

Three occurrences

of two fields

…

COBOL Tables – Overview

 General information on COBOL tables:

 Are one(1)-based in subscripts - not zero-based

 The value within the parenthesis must be: > 0 and <= the table's OCCURS

limit

 Attempts to access COBOL table data beyond its internal size results in a run-time error: S0C4 – index or array out of bounds S0C4 –

 Table rows (or columns) are known as "occurrences"

 Tables an have multiple dimensions

 Up to seven levels of table OCCURS nested within OCCURS in modern COBOL

compilers

 Older COBOL only supported three levels

– (Op-Ed) In standard business programming, tables > three levels deep are rare

 You can use special index datatype values to reference table row data, or you can use subscripts – which are numeric integer variables and values

A COBOL table of 3

dimensions

Why COBOL Tables?

 There are generally two reasons for tables in any language, including COBOL:

1 To simplify repetitive processing patterns and organize related repetitive data

2 To handle design issues that require dynamic, run-time-sized structures

 Example: You want to process quarterly historical data – going back n years, your options are:

* Consider the math to total the above

* …and worse? The quarterly maintenance

* to the data and computations and routines

03 NBR-YEARS PIC S9(4) COMP.

03 QRTRLY-Table OCCURS 0 TO 40 TIMES

DEPENDING ON NBR-YEARS INDEXED BY QTRLY-INDEX.

What can you do with COBOL Tables?

There are four basic categories of things to learn about COBOL tables :

1 Define COBOL tables

 Most of the time in WORKING-STORAGE

 Specific syntax examples follow

2 Load COBOL tables

 From files or databases

 Programmatically from within the PROCEDURE DIVISION

3 Initialize and re-initialize COBOL tables

4 Process COBOL tables – including:

 Using the values procedurally in business logic computations and data manipulation

 Searching the tables for matching values in the PROCEDURE DIVISION – upcoming section

05 element-name OCCURS n TIMES (subordinate items of the table element)

 In the example above

– table-name is the name of an alphanumeric group item table-name

– There would (typically) be one-to-many subordinate items (fields at level 10 or higher) within a structure

 The table element definition (which includes the OCCURS clause) is subordinate to the group item that contains the table

 OCCURS

– Can appear on level: 02  49

– Cannot appear on levels: 01 or 77

 Optional clause: INDEXED BY <idxName>.

– If you declare a COBOL table and include the INDEXED BY clause, the COBOL compiler INDEXED BY will create an internal subscript you will use to reference table occurrences

– Using INDEXED BY can be substantially more efficient than using subscripts – INDEXED BY

particularly for large tables (> 1,000 rows)

Define One-Dimension COBOL Tables – Examples

05 REGION OCCURS 4 TIMES.

10 Q1-SALES PIC 9(5)V99 VALUE ZEROES.

10 Q2-SALES 10 Q2-SALES PIC 9(5)V99 VALUE ZEROES.

10 Q3-SALES 10 Q3-SALES PIC 9(5)V99 VALUE ZEROES.

10 Q4-SALES 10 Q4-SALES PIC 9(5)V99 VALUE ZEROES.

05 FILLER PIC X(09) VALUE "SUNDAY ".

05 FILLER PIC X(09) VALUE "MONDAY " 05 FILLER PIC X(09) VALUE "MONDAY ".

05 FILLER PIC X(09) VALUE "TUESDAY " 05 FILLER PIC X(09) VALUE "TUESDAY ".

05 FILLER PIC X(09) VALUE "WEDNESDAY" 05 FILLER PIC X(09) VALUE "WEDNESDAY".

05 FILLER PIC X(09) VALUE "THURSDAY " 05 FILLER PIC X(09) VALUE "THURSDAY ".

05 FILLER PIC X(09) VALUE "FRIDAY " 05 FILLER PIC X(09) VALUE "FRIDAY ".

05 FILLER PIC X(09) VALUE "SATUDAY " 05 FILLER PIC X(09) VALUE "SATUDAY ".

01 Weekday-Table REDEFINES WEEK-DAY-VALUES

05 WS-Day-of-Week PIC X(09) OCCURS 7 TIMES.

Examples of one-dimension COBOL table loaded by REDEFINE-ing hard-coded

variable values

Load Tables Using Initialize – Syntax

You can load a table:

– Programmatically (from screen, file or database values) – next topic

– REDEFINE constant field values with an REDEFINE OCCURS (previous slides) OCCURS

– Using Initialize – see example below Initialize

– Using the VALUE clause on elementary field definitions.

 Initialize examples, to move the value 3 into each of the elementary numeric data items in a 3

table called TABLE-ONE, shown below, you can code the following statement:

INITIALIZE TABLE-ONE REPLACING NUMERIC DATA BY 3

 To move the character ' X' into each of the elementary alphanumeric data items in X

TABLE-ONE, you can code the following statement:

INITIALIZE TABLE-ONE REPLACING ALPHANUMERIC DATA BY "X"

 When you use the INITIALIZE statement to initialize a table, the table is processed as a INITIALIZE

group item (that is, with group semantics); elementary data items within the group are

recognized and processed

 You can use the REPLACING phrase of the REPLACING INITIALIZE statement similarly to initialize all of INITIALIZE

the elementary fields with these datatypes in a table:

 ALPHABETIC, DBCS, ALPHANUMERIC-EDITED, NATIONAL-EDITED, NUMERIC-EDITED

 The INITIALIZE statement cannot assign values to a variable-length table INITIALIZE

 A table that was defined using OCCURS DEPENDING ON

Load Tables Using INITIALIZE – Example INITIALIZE

Consider the following table declaration:

01 TABLE-ONE

02 Trans-out Occurs 20

05 Trans-code PIC X Value "R".

05 Part-number PIC XX Value "13".

05 Price-fields

10 Unit-price PIC 99V Value 50

10 Discount PIC 99V Value 25

10 Sales-Price PIC 999 Value 375

PROCEDURE DIVISION.

INITIALIZE TABLE-ONE

Replacing Numeric Data By 3 Alphanumeric Data By "X"

The table below shows the content that each of the twenty 12-byte elements Trans-out(n) has

before execution and after execution of the INITIALIZE statement shown above:

 Note – VALUE clauses

initially load the table with specific variable data

Load Tables Dynamically

 If the initial values of your table are

different with each execution of your

program, you can define the table

without initial values

 You can read the changed values into

the table before your program refers

to the table – at the beginning of the

PROCEDURE DIVISION

 Use the PERFORM statement and

either subscripting or indexing.

 When reading data to load your table,

test to make sure that the data does

not exceed the space allocated for the

table (defined by OCCURS) OCCURS

 Use a named value (rather than a

literal) for the item count

 If you end up making the table bigger,

you need to change only one value,

instead of all references to a literal

WORKING-STORAGE SECTION

…

77 PROJECT-INDEX PIC S9(4) COMP.

77 TABLE-MAX PIC S9(4) COMP VALUE 20.

77 SW-END-OF-FILE PIC X(01) VALUE SPACES.

88 END-OF-FILE VALUE 'Y'.

… READ INPUT-FILE AT END MOVE 'Y' TO

EMP-NAME (PROJECT-INDEX) READ INPUT-FILE AT END MOVE 'Y' TO

SW-END-OF-FILE END-PERFORM.

…What's the deal with Perform Varying?

Referring to Values in a One-Dimension COBOL Table - Considerations

 The lowest possible subscript or index value is 1, which references the first occurrence of a table

element

 In a one-dimensional table, the subscript/index corresponds to the row number.

 You can use a literal or a data-name as a subscript

 If a data item that has a literal subscript is of fixed length, the compiler resolves the location of the data item.

 When you use a data-name as a variable subscript, you must describe the data-name as an elementary numeric integer

 If you have defined the COBOL table with INDEXED BY <indexName> - you will use the indexName as the

subscript

 You can increment or decrement an index, or literal or variable subscript by a specified integer

amount For example:

TABLE-COLUMN (SUB1 - 1, SUB2 + 3)

 You can change part of a table element rather than the whole element To do so, refer to the

character position and length of the sub string to be changed For example:

01 ANY-TABLE

05 TABLE-ELEMENT PIC X(10) OCCURS 3 TIMES VALUE "ABCDEFGHIJ"

MOVE "??" TO TABLE-ELEMENT (1) (3 : 2)

 The MOVE statement in the example above moves the string '??' into table element number 1,

beginning at character position 3, for a length of 2 characters.

 We will cover reference modification (3 : 2) later in this course (3 : 2) later in this course

Rules for Subscripts and Indexes

Each subscript/index must be either

 A positive integer

 A data name which represents a positive integer

 A simple expression which evaluates to a positive integer

 The subscript/index must contain a value between 1 and the number of elements

in the table/array inclusive

 When more than one subscript/index is used they must be separated from one another by commas

 One subscript/index must be specified for each dimension of the table

 1 subscript/index for a one dimension table

 2 subscripts/indices for a two dimension table

 3 subscripts/indices for a three dimension table

…

 Subscripts and indexes must be enclosed in parentheses/brackets

 Indexes are manipulated using the COBOL SET keyword:

 SET QTY-IDX TO 1.

 SET QTY-IDX UP BY 1.

 SET QTY-IDX DOWN BY 1.

Putting it All Together – a

complete example

01 Error-Flag-Table Value Spaces.

88 No-Errors Value Spaces.

01 Filler Redefines Error-Flag-Table.

05 Error-Flag Occurs 8 Times

77 ERROR-ON PIC X Value "E".

Indexed By Flag-Index PIC X.

***********************************************************

01 Error-Message-Table.

05 Filler PIC X(25) Value "Transaction Type Invalid".

05 Filler PIC X(25) Value "Shift Code Invalid".

05 Filler PIC X(25) Value "Home Location Code Inval.".

05 Filler PIC X(25) Value "Work Location Code Inval.".

05 Filler PIC X(25) Value "Last Name - Blanks".

05 Filler PIC X(25) Value "Initials - Blanks".

05 Filler PIC X(25) Value "Duplicate Record Found".

05 Filler PIC X(25) Value "Commuter Record Not Found".

01 Filler Redefines Error-Message-Table.

05 Error-Message Occurs 8 Times

Indexed By Message-Index PIC X(25).

PROCEDURE DIVISION PROCEDURE DIVISION.

To Print-Message Perform 260-Print-Report

End-If End-Perform

Referring to a One-Dimension COBOL Table in the Procedure Division

From the course workshop documents, do the following labs:

1 Data Representation and assignment (MOVE statement) Lab

2 Open ended workshop

 Additional Record Concepts

 COBOL Tables – Definition and Language Concepts

 Multi-Dimension COBOL Tables

 Variable Length COBOL Tables

 Searching COBOL Tables

 Processing COBOL Tables With Intrinsic Functions

Topics:

Additional Record and COBOL Table Handling Facilities

Topic Objectives

By the end of this unit you should be able to:

 Describe the COBOL OCCURS clause and code a syntactically correct example for a dimension table

two- Create COBOL two-dimension tables, by redefining values in Working-Storage

 Initialize and load data in a two-dimension COBOL table

 Refer to specific table row/field table occurrences in the Procedure Division of two dim tables

Multiple Dimension COBOL Tables

 Many organizational patterns for data require the use of multi-dimensional arrays to model information accurately.

 Consider the following:

One month of 4 weeks of 7 days

One week of 7 days of many hours