1.4 Database Concepts

Relational databases differ from indexed file systems in several significant ways. These are the logical associations between database concepts and COBOL indexed file concepts:

Indexed File Concept	Database Concept
Directory	Database
File	Table
Record	Row
Field	Column

• Database operations are performed on columns. Indexed file operations are performed on records.

• A COBOL indexed file is logically represented in database table format. Within a table, each column represents one COBOL field; each row represents one COBOL record.

• Database table columns are strictly associated with a particular data type, such as date, integer, or character. In COBOL, data can have multiple type definitions.

For example, for Oracle, a COBOL record that looks like this:

01  terms-record.
    03  terms-code        pic 999.
    03  terms-rate        pic s9v999.
    03  terms-days        pic 9(2).
    03  terms-descript    pic x(15).

would be represented in the database as a table with a format similar to this:

SQL> desc terms;

Name	Null?	Type
TERMS_CODE	NOT NULL	NUMBER (3)
TERMS_RATE		NUMBER (4, 3)
TERMS_DAYS		NUMBER (2)
TERMS_DESCRIPT		CHAR (15)