Moving to full field expansion
Using the millennium
language extensions, you can move gradually toward a solution that fully expands
the date field.
Do the following steps:
- Apply the century window solution, and use this solution until you have
the resources to implement a more permanent solution.
- Apply the internal bridging solution. This way you can use expanded dates
in your programs while your files continue to hold dates in two-digit-year
form. You can progress more easily to a full-field-expansion solution
because there will be no further changes to the logic in the main body of
the programs.
- Change the file layouts and database definitions to use four-digit-year
dates.
- Change your COBOL copybooks to reflect these four-digit-year date fields.
- Run a utility program (or special-purpose COBOL program) to copy files
from the old format to the new format.
- Recompile your programs and do regression testing and date testing.
After you have completed the first two steps, you can repeat the remaining
steps any number of times. You do not need to change every date field in every
file at the same time. Using this method, you can select files for progressive
conversion based on criteria such as business needs or interfaces with other
applications.
When
you use this method, you need to write special-purpose programs to convert your
files to expanded-date form.
Example: converting files to expanded date form
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