Record Descriptions (RDs) are used to accomplish file import and export.
Suppose you have several existing files of data and you want to create a data base and populate it with some or all of the data in these files.
Questions arise.
Do the Table descriptions in the database have to be exact replicas of the existing file formats? Am I restricted at database design time by existing file formats?
The answers are no. Record Descriptions provide a more flexible way of data extraction, conversion, and transfer.
LOAD
and UNLOAD
are the file import and export commands. Both of these commands have a Record Description name (rdname) as part of their syntax:
Where the file to be transfered is an exact replica of a Table, an asterisk (*) can be used in place of the "rdname."
Most of the time the files are not exact replicas. Then, "rdname" refers to an RD that you put in your Application Interface (AI).
Once a database exists, AIs for it can be compiled and recompiled at any time. As requirements come up for importing or exporting files, simply add an RD to a source text AI file and recompile it.
Record Descriptions
A Record Description describes the appearance of an external file. With the RD, we can LOAD data into the database from an external file, or we can UNLOAD data from the database creating (or adding to) an external file.
