Cobol Day 5and 6

COBOL (COMMON BUSINESS ORIENTED LANGUAGE)

Overview

COBOL Fundamentals DAY5

FILES FIXED RECORD LENGTH FILE EMP-NO

ENAME

EAGESALARY

DEPTNO

1-------1011-----------------25-28------35--38 1000000345RAJESH KRISHNAMOORTHY03308900.50030 1000000346RANDY DEDOSAUZ

04407900.50030

1000000347MAHESH RAMARAJAN

05509900.50030

VARIABLE RECORD LENGTH FILE SALESIDSNAME QTY1 LOC1 PRICE1 QTY2 LOC2 PRICE2 QTY3 LOC3 PRICE3 QTY4 LOC4 PRICE4 S101RAJESH

0030 IL

5000

0040

MI

4000

S102RAMESH

0040 PA

4000

0060

WI

6000

S103RAGAVAN

0080 MI

8000

0050

NY

5000

60

CA

6000

Introduction to File processing – Basic terms



Field

Field type and Field size.



Record

Record-Size, Fixed length records and Variable length records.



File

Master files, Transaction files. ACCOUNT File – Master File Payment History- Transaction File

Files, Records, Fields.

 DATA DIVISION.

(e.g. StudentName, DateOfBirth, CourseCode).

FILE SECTION. FD STUDENT-FILE. 01 STUDENT-REC. 05 05 05 05 05

STUD-NAME DOB COURSE-CODE COURSE-NM COURSE-TYPE

We use the term FIELD to describe an item of information we are recording about an object

PIC PIC PIC PIC PIC

X(25). X(10). X(15). X(25). X(5).



We use the term RECORD to describe the collection of fields which record information about an object (e.g. a StudentRecord is a collection of fields recording information about a student).



We use the term FILE to describe a collection of one or more occurrences (instances) of a

Files, Records, Fields. STUDENTS StudId StudName DateOfBirth 9723456 9724567 9534118 9423458 9312876

COUGHLAN RYAN COFFEY O'BRIEN SMITH

DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. 02 StudId 02 StudName 02 DateOfBirth

10091961 31121976 23061964 03111979 12121976

occurrences

Record Type (Template) (Structure) PIC 9(7). PIC X(8). PIC X(8).

How files are processed.

Read a record Based on Structure

Rec1 Rec2 Rec3 Rec4

Read OPEN

Record

Process

Store in

FILE

(One at

Record

Output File

A Time )

Record Buffers Program

DISK STUDENTS

Record Instance

IDENTIFICATION DIVISION. etc. ENVIRONMENT DIVISION. etc. DATA DIVISION. FILE SECTION. RecordBuffer Declaration

Creating a Student Record Student Details. 01 StudentDetails.

 



  

Student Id.

02

StudentId

Student Name.

02

StudentName.

PIC 9(7).

Surname

03 Surname

PIC X(8).

Initials

03 Initials

PIC XX.

Date of Birth

02

DateOfBirth.

Year of Birth

03

YOBirth PIC 99.

Month of Birth

03

MOBirth PIC 99.

Day of Birth

03

DOBirth PIC 99.

Course Code

02

CourseCode

PIC X(4).

Value of grant

02

Grant

PIC 9(4).

Gender

02

Gender

PIC X.

Describing the record buffer in COBOL DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. 02 StudentId 02 StudentName. 03 Surname 03 Initials 02 DateOfBirth. 03 YOBirth 03 MOBirth 03 DOBirth 02 CourseCode 02 Grant 02 Gender

PIC 9(7). PIC X(8). PIC XX. PIC PIC PIC PIC PIC PIC

9(2). 9(2). 9(2). X(4). 9(4). X.



The record type/template/buffer of every file used in a program must be described in the FILE SECTION by means of an FD (file description) entry.



The FD entry consists of the letters FD and an internal file name.

The Select and Assign Clause. ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT StudentFile ASSIGN TO DDNAME.

Physical File

STUDENTS



DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. 02 StudentId 02 StudentName. 03 Surname 03 Initials 02 DateOfBirth. 03 YOBirth 03 MOBirth 03 DOBirth 02 CourseCode 02 Grant 02 Gender

PIC 9(7). PIC X(8). PIC XX. PIC PIC PIC PIC PIC PIC

9(2). 9(2). 9(2). X(4). 9(4). X.

The internal file name used in the FD entry is connected to an external file (on disk or tape) by means of the Select and Assign clause.

Select and Assign Syntax. SELECT FileName ASSIGN TO ExternalFileReference  LINE   SEQUENTIAL]. [ORGANIZATION IS   RECORD 



LINE SEQUENTIAL means each record is followed by the carriage return and line feed characters.



RECORD SEQUENTIAL means that the file consists of a stream of bytes. Only the fact that we know the size of each record allows us to retrieve them.

COBOL file handling Verbs 

OPEN Before your program can access the data in an input file or place data in an output file you must make the file available to the program by OPENing it.



READ The READ copies a record occurrence/instance from the file and places it in the record buffer.



WRITE The WRITE copies the record it finds in the record buffer to the file.



CLOSE You must ensure that (before terminating) your program closes all the files it has opened. Failure to do so may result in data not being written to the file or users being prevented from accessing the file.

OPEN and CLOSE verb syntax

  INPUT      OPEN   OUTPUT  InternalFileName ...   EXTEND     



When you open a file you have to indicate to the system what how you want to use it (e.g. INPUT, OUTPUT, EXTEND) so that the system can manage the file correctly.



Opening a file does not transfer any data to the record buffer, it simply provides access.

Only used for

INPUT Moden

READing Records In A File

Only used for WRITing

output Mode

Records

In A File

Only used for APPENDing

Extend Mode

Records at end of File

READ verb syntax

READ FILE-NAME { INTO IDENTIFIER } AT END { Impreative Statement }



The InternalFilename specified must be a file that has been OPENed for INPUT.



Using INTO Identifier clause causes the data to be read into the record buffer and then copied from there to the specified Identifier in one operation.

 When this option is used there will be two copies of the data. It is the equivalent of a READ followed by a MOVE.



AT END clause it find out whether Read Operation has reached END OF File .

WRITE Syntax.

WRITE record-name FROM IDENTIFIER .



To WRITE data to a file move the data to the record buffer (declared in the FD entry) and then WRITE the contents of record buffer to the file.

How the WRITE works OPEN OUTPUT StudentFile. MOVE "9334567Frank Curtain WRITE StudentDetails. MOVE "9383715Thomas Healy WRITE StudentDetails. CLOSE StudentFile. STOP RUN.

LM051" TO StudentDetails. LM068" TO StudentDetails.

StudentRecord StudentID

StudentName

9 3 3 4 5 6 7 F r a n k

C u r t a i n

Students.Dat

9 3 3 4 5 6 7 F r a n k

EO F

C u r t a i n

Course. L M 0 5 1

L M 0 5 1

How the WRITE works OPEN OUTPUT StudentFile. MOVE "9334567Frank Curtain WRITE StudentDetails. MOVE "9383715Thomas Healy WRITE StudentDetails. CLOSE StudentFile. STOP RUN.

LM051" TO StudentDetails. LM068" TO StudentDetails.

StudentRecord StudentID

StudentName

9 3 8 3 7 1 5 T h o ma s

H e a l y

Students.Dat

9 3 3 4 5 6 7 F r a n k C u r t a i n 9 3 8 3 7 1 5 T h o ma s H e a l y

EOF

Course. L M 0 6 8

L M 0 5 1 L M 0 6 8

IDENTIFICATION DIVISION. PROGRAM-ID. SeqWrite. ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT StudentFile ASSIGN TO DDNAME ORGANIZATION IS LINE SEQUENTIAL.

Assign File To DDNAME (Physical Sequential File)

DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. Declaring File Structure 02 StudentId PIC 9(7). 02 StudentName. 03 Surname PIC X(8). 03 Initials PIC XX. 02 CourseCode PIC X(4). 02 Gender PIC X. WORKING-STORAGE SECTION. Opened the File For Writing Recs 01 CHOICE PIC X(1) VALUE ‘Y’. PROCEDURE DIVISION. 001-MAIN-PARA. OPEN OUTPUT StudentFile. DISPLAY "Enter student details Enter the choice for Continue ". PERFORM GetStudentDetails. PERFORM UNTIL CHOICE = ‘N’ WRITE StudentDetails Write a Record in a File PERFORM GetStudentDetails END-PERFORM. CLOSE StudentFile. STOP RUN. GetStudentDetails. DISPLAY ‘ENTER STUDENT-ID’. ACCEPT STUDENTID. DISPLAY ‘ENTER STUDENT NAME with Intial:’. ACCEPT STUDENTNAME. DISPLAY ‘ENTER COURSECODE’. ACCEPT COURSECODE. DISPLAY ‘ENTER GENDER:’. ACCEPT GENDER. DISPLAY ‘ENTER THE CHOICE OF CONTINUATION (Y/N):’. ACCEPT CHOICE.

Getting values for Records to be written In File

Sequential write

Write cont..

IDENTIFICATION DIVISION. PROGRAM-ID. SeqRead. AUTHOR. Michael Coughlan.

Assign File To DDNAME

ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT StudentFile ASSIGN TO dd-name ORGANIZATION IS LINE SEQUENTIAL. DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. 02 StudentId 02 StudentName. 03 Surname 03 Initials 02 CourseCode 02 Gender

(Physical Sequential File)

Declaring File Structure PIC 9(7). PIC PIC PIC PIC

X(8). XX. X(4). X.

Opened the File For Reading Recs

PROCEDURE DIVISION. Begin. OPEN INPUT StudentFile READ StudentFile AT END MOVE HIGH-VALUES TO StudentDetails END-READ PERFORM UNTIL StudentDetails = HIGH-VALUES DISPLAY StudentId SPACE StudentName SPACE CourseCode READ StudentFile AT END MOVE HIGH-VALUES TO StudentDetails END-READ END-PERFORM CLOSE StudentFile STOP RUN.

Read a Record in a File till END OF File is reached

Display values at SPOOL

Close a File which Is Opened

How the READ works StudentRecord StudentID

9 3 3 4 5 6 7 F r a n k

9 9 9 9

3 3 3 3

3 8 4 7

4 3 7 8

5 7 2 8

Course.

StudentName

6 1 9 1

7 5 2 1

F T T B

r h o i

a o n l

C u r t a i n

n k C u ma s H y O ‘ B l y D o

r e r w

t a i n

a l a e

i n y n s

L M 0 5 1

L L L L

EOF PERFORM UNTIL StudentRecord = HIGH-VALUES READ StudentRecords AT END MOVE HIGH-VALUES TO StudentRecord END-READ END-PERFORM.

M M M M

0 0 0 0

5 6 5 2

1 8 1 1

How the READ works StudentRecord StudentID

9 3 8 3 7 1 5 T h o ma s

9 9 9 9

3 3 3 3

3 8 4 7

4 3 7 8

5 7 2 8

Course.

StudentName

6 1 9 1

7 5 2 1

F T T B

r h o i

a o n l

H e a l y

n k C u ma s H y O ‘ B l y D o

r e r w

t a i n

a l a e

i n y n s

L M 0 6 8

L L L L

EOF PERFORM UNTIL StudentRecord = HIGH-VALUES READ StudentRecords AT END MOVE HIGH-VALUES TO StudentRecord END-READ END-PERFORM.

M M M M

0 0 0 0

5 6 5 2

1 8 1 1

How the READ works StudentRecord StudentID

9 3 4 7 2 9 2 T o n y

9 9 9 9

3 3 3 3

3 8 4 7

4 3 7 8

5 7 2 8

Course.

StudentName

6 1 9 1

7 5 2 1

F T T B

r h o i

a o n l

O ‘ B r i a n

n k C u ma s H y O ‘ B l y D o

r e r w

t a i n

a l a e

i n y n s

L M 0 5 1

L L L L

EOF PERFORM UNTIL StudentRecord = HIGH-VALUES READ StudentRecords AT END MOVE HIGH-VALUES TO StudentRecord END-READ END-PERFORM.

M M M M

0 0 0 0

5 6 5 2

1 8 1 1

How the READ works StudentRecord StudentID

9 3 7 8 8 1 1 B i l l y

9 9 9 9

3 3 3 3

3 8 4 7

4 3 7 8

5 7 2 8

Course.

StudentName

6 1 9 1

7 5 2 1

F T T B

r h o i

a o n l

D o w n e s

n k C u ma s H y O ‘ B l y D o

r e r w

t a i n

a l a e

i n y n s

L M 0 2 1

L L L L

EOF PERFORM UNTIL StudentRecord = HIGH-VALUES READ StudentRecords AT END MOVE HIGH-VALUES TO StudentRecord END-READ END-PERFORM.

M M M M

0 0 0 0

5 6 5 2

1 8 1 1

How the READ works StudentRecord StudentID

Course.

StudentName

                        

HIGH-VALUES 9 9 9 9

3 3 3 3

3 8 4 7

4 3 7 8

5 7 2 8

6 1 9 1

7 5 2 1

F T T B

r h o i

a o n l

n k C u ma s H y O ‘ B l y D o

r e r w

t a i n

a l a e

i n y n s

L L L L

EOF PERFORM UNTIL StudentRecord = HIGH-VALUES READ StudentRecords AT END MOVE HIGH-VALUES TO StudentRecord END-READ END-PERFORM.

M M M M

0 0 0 0

5 6 5 2

1 8 1 1

Sequential read.

SEQUENTIAL READ Program cont..

REWRITE verb REWRITE is used to update an existing record in the file which has been read in the program Syntax REWRITE record-name [FROM data-name] [END-REWRITE] Note: The REWRITE statement can only be used if the file is opened in the I-O mode and its execution must be preceded by the successful READ statement on the file. The REWRITE statement replaces last read record

REWRITE 

If a file is opened in the I-O mode and a record has been read successfully into the record buffer, then we



can use the REWRITE statement to update an existing record. Similar to the WRITE statement, the REWRITE



statement can be used with FROM option for writing data directly from a WORKING-STORAGE variable to the



required file.

IDENTIFICATION DIVISION. PROGRAM-ID. SeqWR. ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT StudentFile ASSIGN TO DDNAME ORGANIZATION IS LINE SEQUENTIAL. DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. 02 StudentId PIC 9(7). 02 StudentName. 03 Surname PIC X(8). 03 Initials PIC XX. 02 CourseCode PIC X(4). 02 Gender PIC X.

PROCEDURE DIVISION. Begin. OPEN INPUT-OUTPUT StudentFile READ StudentFile AT END MOVE HIGH-VALUES TO StudentDetails END-READ IF STUDENTID = S10012 MOVE ‘C108’ TO Coursecode REWRITE STUDENTDETAILS END-IF. PERFORM UNTIL StudentDetails = HIGH-VALUES DISPLAY StudentId SPACE StudentName SPACE CourseCode READ StudentFile AT END MOVE HIGH-VALUES TO StudentDetails END-READ IF STUDENTID = S10012 MOVE ‘C108’ TO Coursecode REWRITE STUDENTDETAILS END-IF

END-PERFORM CLOSE StudentFile STOP RUN.

Sequential Re-write

SEQUENTIAL REWRITE Cont….

The CALL Verb

Objectives    

Define CALL statement CALL BY CONTENT/REFERENCE Define LINKAGE SECTION Cover LINKAGE SECTION & JCL Parameters

CALL Syntax

CALL statement transfers control from one object program to another within run unit

CALL Example CALL “PROGA” USING…. ON EXCEPTION SET GOOD-CALL TO TRUE NOT ON EXCEPTION SET BAD-CALL TO TRUE END-CALL

CALL BY CONTENT/REFERENCE 

CALL BY REFERENCE technique allows the sub-program to access and process the data-items in the caller’s storage



CALL BY CONTENT technique allows the sub-program to access and process a copy of the data-items from the caller’s storage. The subprogram can not change the original data values in the caller’s storage

LINKAGE SECTION 

The LINKAGE SECTION of DATA DIVISION describes data made available from another program



Storage is not RESERVED



Value clause can not be specified for items other than level-88 items



EXTERNAL clause can not be specified in LINKAGE SECTION

CALL with LINKAGE Example DATA DIVISION. … WORKING-STORAGE SECTION. 01 PARM-LIST. 05 PART-NO PIC X(4). 05 USA-SALES PIC 9(5). …

PROGA LINKAGE SECTION. 01 USING-LIST. 10 PART-ID PIC X(4).

PROCEDURE DIVISION.

10 SALES PIC 9(5).

… CALL “PROGA” USING PARM-LIST. …

PROCEDURE DIVISION USING USING-LIST. …. GOBACK.

LINKAGE SECTION & JCL Parameters 

User-parameters can be passed to the COBOL program being executed via the PARM parameter of the EXEC statement: //STEPNAM EXEC PGM=XXXX,…, //



PARM=‘USER-PARAMETER’

Access to the user-parameter string requires LINKAGE SECTION definitions:

CALL Parameters

CALL "ProgramName" USING P1, P2, P3, P4.

PROCEDURE DIVISION USING P2, P4, P1, P3.

CALL Parameters

CALL "ProgramName" USING P1, P2, P3, P4.

PROCEDURE DIVISION USING P2, P4, P1, P3. Positions Correspond - Not Names

Parameter Passing Mechanisms

CALL .. BY REFERENCE

CALLed Program

Parameter Passing Mechanisms Address of Data Item

CALL .. BY REFERENCE

Direction of Data Flow

CALLed Program

Parameter Passing Mechanisms Address of Data Item

CALL .. BY REFERENCE

Direction of Data Flow

CALL .. BY CONTENT

CALLed Program

CALLed Program

Copy of Data Item

Parameter Passing Mechanisms Address of Data Item

CALL .. BY REFERENCE

Direction of Data Flow

Direction of Data Flow

CALL .. BY CONTENT Data Item

Copy of Data Item

CALLed Program

CALLed Program Address of Copy

Passing by reference and value COBOL provides two ways of passing parameters to the called program using the CALL statement. They are -

1) By REFERENCE

 CALL SUBPGM1 USING WS-NUM1. 2) BY VALUE

 CALL SUBPGM1 USING BY CONTENT WS-NUM1 BY REFERENCE WS-NUM2 BY REFERENCE WS-NUM3.

CALL

Example

SAMPLE CALL PROGRAM

Overview

CALLING – CALLED program. An example The CALLING program

CALLING – CALLED program. An example The CALLED program

We can use the variables passed by the calling program, in the procedure division of the called program. The name need not be the same.

Define variables passed by the calling program in the linkage section

Procedure division statement modified to include the passed variables from the calling program in the same sequence as given in the call statement

CALLING – CALLED program. An example

Output spool display

CALL - Types Basically there are two types of calls –

c)

STATIC call A static call occurs when you use the CALL statement in a program that is compiled with the NODYNAM compiler option. Regardless of whether it is called or not, a statically called program is loaded into storage

CALL TYPES (DYNAMIC call )

 A dynamic call occurs when you use the CALL statement in a program compiled with the DYNAM compiler option.

 In this case the CALLing and CALLed programs are each processed separately by the link-editor. A dynamically called program is loaded only when it is called at run time.

 We generally use a dynamic call statement when you are concerned about ease of maintenance. Applications do not have to be re-link-edited when Dynamically called subprograms are changed.

Dynamic vs. Static Calls 

Dynamic calls take more processing than static calls. However, a dynamic call may use less total storage than a static call.



A statically called program cannot be deleted, but a dynamically called program can be deleted.



Using a dynamic call and then a CANCEL statement to delete the dynamically called program after it is no longer needed in the application (and not after each CALL to it) may require less storage than using a static call.



Use Dynamic CALL if the subprograms are very large or less frequently used (called only on a few conditions).



In such case, the use of static calls might require too much main storage. Less total storage may be required to call and cancel one, then call and cancel another, THAN to statically call both.

STATIC CALL EXAMPLE

Overview

Static Call – Simple Program

STATIC CALL: Main Program

STATIC CALL: Compile JCL

STATIC CALL: RUN JCL

Dynamic call :Sub Program

Dynamic Call : Main Program

Dynamic Call Main Pgm Compile JCL

DYNAMIC CALL MAIN PROGRAM RUN JCL

Rules for coding CALLed programs



The called program needs to have a LINKAGE SECTION. This must appear after the WORKING-STORAGE SECTION in the DATA DIVISION. The variables in the linkage section have to independent items.



The PROCEDURE DIVISION needs to have a USING clause. This identifies the variables passed to the program and their ordering.



Entries in the LINKAGE SECTION can be in any order, but the entries in the USING clause must be in the order of their usage in the CALL statement of the CALLing program.



Instead of a STOP RUN statement, the called program must contain an EXIT PROGRAM statement to transfer control back to the calling program.

SORTING AND MERGING DATA FILES

Overview

COBOL –Sorting 

Records in files must be sorted into specific sequences for Updating, Querying or Generating Reports.



Sorting is a common procedure used for arranging records into a specific order so that sequential processing can be performed.



Sorting is done on the basis of a key field

COBOL – Sort syntax SORT

File-name-1 { ON

DESCENDING

KEY Data-name-1. . . }

ASCENDING USING File-name-2 GIVING File-name-3.

 

Multiple keys can be used for sorting. Records may be sorted using either numeric or non-numeric key fields.

COBOL – Sort e.g. SORT SORT-FILE ON ASCENDING KEY EMP-NO ON ASCENDING KEY E-NAME ON ASCENDING KEY E-LEVEL USING INPUT-FILE GIVING OUTPUT-FILE.

  

INPUT FILE : File of unsorted records. SORT FILE : File for temporary storage during sorting. OUTPUT FILE : File of sorted output records.

COBOL –Sort – SD 

Sort file is defined with an SD entry and has no label records clause.

E.g.:

SD SORT-FILE. 01 SORT-REC. 05

S-DEPTNO PIC

99.

05

S-DEPTNAME

PIC

X(10).

COBOL – Sort – Input Procedure 

Sort statement can also be used to perform some processing of incoming records just before they are sorted.



The input procedure processes data from the incoming file prior to sorting.

DATA DIVISION. FILE SECTION. FD StudentFile. 01 StudentDetails. 02 StudentId 02 StudentName. 03 Surname 03 Initials 02 DateOfBirth. 03 YOBirth 03 MOBirth 03 DOBirth 02 CourseCode 02 Grant 02 Gender

PIC 9(7). PIC X(8). PIC XX. PIC PIC PIC PIC PIC PIC

9(2). 9(2). 9(2). X(4). 9(4). X.



The StudentFile is a sequential file sequenced upon ascending StudentId.



Write a program to display the number of students taking each course. How?

Simplified Sort Syntax.



The WorkFileName identifies a temporary work file that the SORT process uses for the sort. It is defined in the FILE SECTION using an SD entry.



Each SortKeyIdentifier identifies a field in the record of the work file upon which the file will be sequenced.



When more than one SortKeyIdentifier is specified, the keys decrease in significance from left to right (leftmost key is most significant, rightmost is least significant).



InFileName and OutFileName, are the names of the input and output files. These files are automatically opened by the SORT. When the SORT executes they must not be already open.

Sort Example. FD 01 SD 01

FD 01

SalesFile. SalesRec. 02 FILLER

PIC X(10).

WorkFile. WorkRec. 02 WSalesmanNum 02 FILLER

PIC 9(5). PIC X(5).

SortedSalesFile. SortedSalesRec. 02 SalesmanNum PIC 9(5). 02 ItemType PIC X. 02 QtySold PIC 9(4).

PROCEDURE DIVISION. Begin. SORT WorkFile ON ASCENDING KEY WSalesmanNum USING SalesFile GIVING SortedSalesFile. OPEN INPUT SortedSalesFile.

ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT WorkFile ASSIGN TO DDNAME SD 01

WorkFile. WorkRecord. 02 ProvinceCode 02 SalesmanCode 02 FILLER

PIC 9. PIC 9(5). PIC X(19).

PROCEDURE DIVISION. Begin. SORT WorkFile ON ASCENDING KEY ProvinceCode DESCENDING KEY SalesmanCode USING UnsortedSales GIVING SortedSales. OPEN INPUT SortedSales.

How the SORT works. SalesFile

SortedSalesFile

Unsorted Records

SORT Process

Sorted Records

WorkFile SORT WorkFile ON ASCENDING KEY WSalesmanNum USING SalesFile GIVING SortedSalesFile.

INPUT FILE

OUTPUT File

SIMPLE SORT PROGRAM

SIMPLE SORT PROGRAM

RUN JCL

SIMPLE SORT OUTPUT

COMPLEX SORT

Overview

COBOL – SORT Input Procedure – Syntax SORT file-name-1 { ON ASCENDING DESCENDING

KEY data-name-1. . . }. . .

{ INPUT PROCEDURE IS procedure-name-1 [ {THRU / THROUGH} ] procedure-name-2 ] }

{ USING file-name-2 . . . }

GIVING file-name-3.

How the INPUT PROCEDURE works. SalesFile

Unsorted Records

Unsorted Hat Records

SortedSalesFile

SORT Process

Sorted Records

SelectHatSales WorkFile SORT WorkFile ON ASCENDING KEY WSalesmanNum INPUT PROCEDURE IS SelectHatSales GIVING SortedSalesFile.

INPUT PROCEDURE Template

OPEN INPUT InFileName READ InFileName RECORD PERFORM UNTIL Condition RELEASE SDWorkRec READ InFileName RECORD END-PERFORM CLOSE InFile

INPUT PROCEDURE - Example FD 01

SalesFile. SalesRec. 88 EndOfSales VALUE HIGH-VALUES. 02 FILLER PIC 9(5). 02 FILLER PIC X. 88 HatRecord VALUE "H". 02 FILLER PIC X(4). SD WorkFile. 01 WorkRec. 02 WSalesmanNum PIC 9(5). 02 FILLER PIC X(5). FD SortedSalesFile. 01 SortedSalesRec. 02 SalesmanNum PIC 9(5). 02 ItemType PIC X. 02 QtySold PIC 9(4). PROCEDURE DIVISION. Begin. SORT WorkFile ON ASCENDING KEY WSalesmanNum INPUT PROCEDURE IS SelectHatSales GIVING SortedSalesFile.

COBOL – SORT Input Procedure – e.g. SORT WorkFile ON ASCENDING KEY WSalesmanNum INPUT PROCEDURE IS SelectHatSales GIVING SortedSalesFile.

In the paragraph check-valid-para :

   

Open input file. Check for validity Release the record Close the file

After that control is passed to SORT.

COBOL – SORT Release 

The input procedure opens the input file, processes input records and releases them into the sort file. It is similar to writing a record to the sort file.



The format of RELEASE is : RELEASE

Sort-record-name-1 [ FROM Identifier-1 ]

COBOL – SORT Release (cont’d) For releasing the processed record for Sorting :

 

Move input record to the sort record. Release each sort record, which makes it available for sorting.

E.g. RELEASE-PARA. MOVE IN-REC TO SORT-REC. RELEASE SORT-REC.

COBOL – SORT Typical Program MAIN-PARA. SORT SORT-FILE ON ASCENDING KEY ORDER-NO INPUT PROCEDURE TEST-PARA GIVING OUT-FILE. STOP RUN. TEST-PARA. OPEN INPUT IN-FILE. PERFORM PROCESS-PARA UNTIL NO-MORE-RECORDS = ‘NO’ CLOSE IN-FILE. PROCESS-PARA. READ IN-FILE AT END

MOVE ‘NO’ TO NO-MORE-RECORDS.

IF QTY = ZEROS CONTINUE ELSE MOVE IN-REC TO SORT-REC RELEASE SORT-REC END-IF.

Complex Sort :INPUT FILE

COMPLEX SORT:INPUT PROCEDURE

COMPLEX SORT:INPUT PROCEDURE

COMPLEX SORT: INPUT PROCEDURE

COMPLEX SORT:RUN JCL

COMPLEX SORT : OUTPUT FILE

COMPLEX SORT : Input File

COBOL SORT: OUTPUT PROCEDURE

COBOL – SORT Output Procedure 

In case of sort if the giving option is used, then the sorted records are automatically written onto the out-file after they are used.



Instead of giving option an output procedure can be used.



In an input procedure we RELEASE records to a sort file rather than WRITING them. In an output procedure we RETURN records from the sort file rather than READING them.

COBOL – SORT Output Procedure – Syntax SORT file-1 { ON

DESCENDING KEY data-name-1..} ASCENDING

{OUTPUT PROCEDURE IS proc-3 } {GIVING file-2 . . . }

COBOL – SORT Return 

Records are returned from the sort file using RETURN statement.

RETURN SORT-FILE-NAME-1

AT END [ NOT AT END ] [END-RETURN].

COBOL – SORT Output Procedure – e.g. MAIN-PARA. SORT WORK-FILE

USING IN-FILE OUTPUT PROCEDURE CHECK-PARA. STOP RUN.



In the paragraph CHECK-PARA:

 Open output file.  Return records from sort file.  Process records before writing to Out-file.  Close the file.

COBOL – SORT Output Procedure – e.g. After the records have been sorted but before they are written into the output file:

 

Move sort record to the output area. Write each sort record to the output file.

E.g.: WRITE-PARA. WRITE SORT-REC FROM WORK-REC.

COBOL – SORT Typical Program MAIN-PARA. SORT SORT-FILE ON ASCENDING KEY TRANS-NO USING INPUT-FILE OUTPUT PROCEDURE CALC-PARA. STOP RUN. CALC-PARA. OPEN OUTPUT OUTPUT-FILE. PERFORM PROCESS-PARA UNTIL NO-MORE-RECORDS = ‘NO’ CLOSE OUTPUT-FILE. PROCESS-PARA. RETURN SORT-FILE AT END MOVE ‘NO’ TO NO-MORE-RECORDS. IF AMT-OF-PURCHASE > 6000 MOVE 0.02 TO DISCOUNT ELSE MOVE 0.00 TO DISCOUNT END-IF. WRITE OUT-REC FROM SORT-REC.

COMPLEX SORT: Output Procedure

Complex Sort : Output Procedure

COMPLEX SORT : OUTPUT PROCEDURE

COMPLEX SORT : RUN JCL

COMPLEX SORT: OUTPUT DATA

COBOL – Merge 

COBOL has a MERGE statement that will combine two or more files into a single file.



The MERGE statement automatically handles the opening, closing, and any I-O (read/write functions) associated with the files.



The files to be merged must be in sequence by the key-field (ascending or descending).

COBOL – Merge Merge syntax MERGE file-1 { ON

ASCENDING DESCENDING

USING file-2 { file-3 } . . . OUTPUT PROCEDURE IS proc-1 GIVING {file-4}.

KEY data -1}

COBOL – Merge Typical Program FILE CONTROL. SELECT IN-FILE1

ASSIGN

TO E-FILE1.

SELECT IN-FILE2

ASSIGN

TO E-FILE2.

SELECT M-FILE SELECT OUT-FILE

ASSIGN ASSIGN

TO WORK. TO E-FILE.

DATA DIVISION. FD

IN-FILE1.

01

IN-REC1

FD

IN-FILE2.

01

IN-REC2

SD

M-FILE.

01

PIC

X(100).

PIC

X(100).

PIC

X(100).

M-REC. 05 KEY-FIELD

PIC

05 REST-OF REC PIC FD

OUT-FILE.

01

OUT-REC

X(5). X(100).

PROCEDURE DIVISION. MAIN-PARA. MERGE M-FILE ON ASCENDING KEY KEY-FIELD USING IN-FILE1, IN-FILE2 GIVING OUT-FILE STOP RUN

MERGE EXAMPLE

Overview

COBOL – Sort & Merge Summary 

SORT is used for sorting records in either ascending or descending order



Processing of records can be carried out before or after sorting by using Input or Output procedures or using both



Merge is used to merge two or more files

END OF SORT & MERGE