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
|
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) |