📅  最后修改于: 2023-12-03 15:35:37.667000             🧑  作者: Mango
VSAM(Virtual Storage Access Method)是IBM公司开发的一种数据存储和检索技术,是IBM公司推出的主机操作系统z/OS(前称OS/390, MVS)上的一种数据存储管理系统。RRDS(Relative Record Data Set)是VSAM的一种存储方式,VSAM-RRDS基于RRDS存储方式,是一种随机存取文件。
VSAM-RRDS主要用于存储大量的数据,数据访问频繁,要求快速随机存取。适合用来存储一些需要实时查询和更新的数据,如存储银行账户信息和交易记录等。
IDENTIFICATION DIVISION.
PROGRAM-ID. MYPROG.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT MYFILE ASSIGN TO VSAMRRDS
ORGANIZATION IS RELATIVE
ACCESS MODE IS RANDOM
RELATIVE KEY IS MYKEY.
DATA DIVISION.
FILE SECTION.
FD MYFILE
BLOCK CONTAINS 0 RECORDS
RECORD CONTAINS 80 CHARACTERS
RECORDING MODE IS F
DATA RECORD IS MYRECORD.
01 MYRECORD.
05 FILLER PIC X(4).
05 NAME PIC X(20).
05 SALARY PIC 9(7)V99.
05 FILLER PIC X(49).
WORKING-STORAGE SECTION.
01 WS-VAR.
05 WS-NAME PIC X(20) VALUE "JANE DOE".
05 WS-SALARY PIC 9(7)V99 VALUE 10000.00.
05 WS-REC-LENGTH PIC 99 VALUE 80.
05 WS-MYKEY PIC 9(5) VALUE 10.
PROCEDURE DIVISION.
MAIN.
OPEN I-O MYFILE.
READ MYFILE RECORD INTO MYRECORD
KEY IS MYKEY
INVALID KEY DISPLAY "INVALID KEY".
MOVE WS-NAME TO NAME.
MOVE WS-SALARY TO SALARY.
WRITE MYFILE RECORD FROM MYRECORD
INVALID KEY DISPLAY "WRITE ERROR".
READ MYFILE RECORD INTO MYRECORD
KEY IS MYKEY
INVALID KEY DISPLAY "INVALID KEY".
DISPLAY "NAME: ", NAME.
DISPLAY "SALARY: ", SALARY.
CLOSE MYFILE.
STOP RUN.
以上是一个使用VSAM-RRDS进行随机存取的COBOL程序示例,其中MYFILE
是一个VSAM-RRDS文件,通过READ
和WRITE
指令可以进行记录的读写。