In sequential file organization, records cannot be deleted. Syntax OPEN "mode" file-name. Rewrite verb overwrites the last record read. If the access mode is random or dynamic, then to write a record, the file must open in Output mode or I-O mode.
It can be used only after a successful Read operation. Read Verb Read verb is used to read the file records. The record last read by the Read statement is deleted in case of sequential access mode.
Close Open Verb Open is the first file operation that must be performed. If Open is successful, then only further operations are possible on a file. If this READ is skipped for any reason, the program will loop without end. INTO clause is optional.
The logic shown in this program is the kind used in many companies and has become an industry standard. Before inserting records into the file, move the values into the record buffer and then perform write verb.
If file access mode is Random or Dynamic, then extend mode cannot be used.
If a sequential file is used and the file is holding some records, then the existing records will be deleted first and then new records will be inserted in the file. It makes no changes to the file.
At each read verb, only one record can be read into the file structure. This program basically just copies an input file to an output file.
Only after opening a file, the variables in the file structure are available for processing. The link between program and file is lost.
It typically formats output lines and them writes them. This program reads every record in a file and does some processing with each record read. Once the record is written, it is no longer available in the record buffer.
This program can be compiled and executed using JCL on Mainframes where it will display all the records present in the file. Here are some other types of programs that fall into the same logic pattern: It will not produce a report, nor will it reformat the records in any way.
In this mode, we can only read the file, no other operations are allowed on the file. If the access mode is sequential, then to write a record, the file must open in Output mode or Extend mode. It will not happen so in case of an indexed file or a relative file.
File should be opened in I-O mode for rewrite operations. Write statement can be used with FROM option to directly write records from the working storage variables. Suppose the input file data available in the input.
In random access mode, specify the record key and then perform the Delete operation. At each read statement, the file pointer is incremented and hence the successive records are read.
In this mode, records are inserted at the end. From is an optional clause. The function of read is to fetch records from a file. Close Verb Close verb is used to close a file. Compliments of Gabe Gargiulo, author of several recent books on programming and modern languages, available at Amazon.
This is a simple COPY program. The access mode must be sequential or dynamic. Major logic decisions are normally done there, although this program has none. File must be opened in I-O or Input mode. The file must be opened in I-O mode.COBOL Copy File for QSAM The following (mint-body.com) is a sample of the mainframe COBOL copy file that contains the record format for the QSAM file that is read as a sequential input file.
file-control. SELECT WS-INFILE ASSIGN TO INFILE ORGANIZATION IS INDEXED ACCESS MODE IS RANDOM RECORD KEY IS INP-EMPID FILE STATUS IS. Use the READ statement to retrieve (READ) records from a file. To read a record, you must have opened the file INPUT or I-O.
Your program should check the file status key after each READ. COBOL File Handling Verbs - Learn Cobol in simple and easy steps starting from basic to advanced concepts with examples including Overview, Environment Setup, Program Structure, Basic Syntax, Data Types, Basic Verbs, Data Layout, Condition Statements, Loop Statements, String Handling, Table Processing, File Handling, File Organization, File Access Mode, File.
The American Programmer: Home: Books on Mainframe Programming: Sample Cobol code: The VSAM File Read Sequentially in a COBOL program Sample Cobol code: The VSAM KSDS, Read Randomly in a COBOL program This program reads every record in a file and does some processing with each record read.
Our sample program will just write.
set file-not-eof to true perform until file-eof read file at end set file-eof to true not at end perform process-record end-read end-perform Good luck, hope it works out for you.
Writing solid COBOL can be very tough.Download