Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1997-12-18
2001-05-22
Homere, Jean R. (Department: 2777)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000
Reexamination Certificate
active
06237002
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns the field of data processing using computers. More specifically, this invention relates to solutions to problems resulting from the use of two digits to signify the year in stored dates in databases and computer systems.
BACKGROUND OF THE INVENTION
A common requirement of computer systems is the processing of date-oriented information in chronological order. Because of the high cost of memory in computing systems and also because of the convenience, date-oriented information has commonly been stored in a format in which the year portion of the date associated with the information is represented by two digits. Thus, the year 1996 is commonly represented in computer applications as “96.” Sorting and sequencing such information has not presented any problem up to now because such two-digit year designators (along with other designators representing days, weeks, and/or months) could easily be placed in their proper order. Current computer and software systems can easily compare, for example, 94 and 96, as representing 1994 and 1996 dates, and can accordingly arrange information associated with the dates and/or the dates themselves in proper chronological order.
However, present computer systems which process two-digit year data will not be able to adequately process date-oriented information associated with dates in the year 2000 and beyond. Dates during the year 2000 have a two-digit year designation of 00; without any additional information, a computer will organize date data having a year designation 00 as though the year was 1900. The result is that application programs relying on dates in their correct chronological order will be unable to operate properly with two-digit year date designations representing dates from both the 20
th
and 21
st
centuries.
Operations with date values are commonly performed by means of “windowing.” Windowing is a technique in which only a portion of the total data is visible at any one time. Windows may be either fixed or sliding, with a fixed window having a definite starting and ending year, while a sliding or dynamic window provides for a user-defined starting and ending point. The common method of operating with two-digit year designations uses a fixed window of 100 years beginning with the digits 00 (representing 1900) and ending with 99 (representing 1999), the century designator (i.e. “19”) being implied.
Various solutions have been suggested to address the impending problems associated with two-digit year designations spanning multiple centuries. One principal solution involves data expansion, which is the conversion of all two-digit year designations to four-digit year designations. In this way, sequencing and sorting of date data can occur as it always has. However, this solution has numerous disadvantages, foremost among which is the expense of conversion in terms of additional memory requirements and associated costs. Another problem is that data expansion is not easily retrofitted to existing systems due to incompatibility with existing data and software. Yet another problem with this solution includes significant amounts of system downtime during the conversion.
Another proposed solution is to make changes in the data accessing procedures. Use of two-digit year designators is retained, along with the concomitant out-of-sequence condition of the associated information. Instead, the logic of application programs which operate on the data is modified to retrieve data records using multiple passes. A first pass may, for example retrieve date-oriented information associated with 20
th
century dates, and a second pass may retrieve 21
st
century information. The principal disadvantages inherent in this proposed solution is that it changes the processing logic in application programs and that it is quite awkward to implement.
Yet another proposed solution is to modify application programs so that the programs change the year designation of a datum read from a master file or data storage. One example is U.S. Pat. No. 5.600,836 to Alter, which describes a system and method by which a virtual boundary is erected between a database or other data storage or input means containing date-oriented information and the application program using such information. The boundary is a date conversion which applies to any information crossing the boundary, i.e. being called from storage to an application program, or being output or stored from the result of the application program. Raw data are altered at the boundary by adding or subtracting a given value from the raw data and then performing operations on the altered data. This proposed solution has the drawback that it can only be used with a limited window of years.
IBM Corporation has developed versions of its Information Management System (IMS) database and processing software which is able to process some dates in 2000 and beyond. The IBM solution, like that of the Alter patent, is to add a sum to two-digit year designators representing dates in the years 2000-2059 inclusive. This is accomplished by adding 10 in hexadecimal format to the tens digit of a two-digit year designator having a tens digit of 0-5 inclusive. For example, the year 2010 would be represented by the two-digit year designator 10. The IBM method would add a hexadecimal equivalent of 10 to the tens digit, making the two-digit year designator B0 (where B is the hexadecimal digit equivalent to the value 11 in base-10 format). One disadvantage to the IBM solution is that it only works for a certain window of dates, in the above example dates between 1960 and 2059 inclusive.
Accordingly, there still exists a need for a method for easily and cost-effectively retaining the use of two-digit years for date-oriented information associated with dates in more than one century while maintaining the information in correct chronological sequence.
SUMMARY OF THE INVENTION
The present invention is a data encoding and decoding method which meets the foregoing need. Specifically, it comprises the encoding of date values associated with date-oriented information prior to processing such information and decoding the date values after processing is complete. The encoding of date values comprises changing the sequence of the hexadecimal characters representing the date portions of date-oriented information. Subroutines called prior to and after input and output operations carry out the method of the present invention.
In a specific embodiment of the present invention, date values representing dates prior to 2000 are not encoded, and therefore date values representing dates in the 20
th
century do not require conversion. Date values representing dates in 2000 and beyond are encoded by changing the order of the hexadecimal characters representing them. After encoding, the date values may be sorted and sequenced or otherwise operated on by a desired application program. Following the operation of the application program, the data representing dates in 2000 and beyond are decoded for storage or output. In this way, existing dates within database structures and other forms of data storage do not need to be modified. Information Management System (IMS) database definitions are not changed, original program calls remain intact, and phased implementation of application programs is allowed.
REFERENCES:
patent: 5600836 (1997-02-01), Alter
patent: 5630118 (1997-05-01), Shaughnessy
patent: 5644762 (1997-07-01), Soeder
patent: 5668989 (1997-09-01), Mao
patent: 5719826 (1998-02-01), Lips
patent: 5758336 (1998-05-01), Brady
patent: 5761668 (1998-06-01), Adamchick
patent: 5806063 (1998-09-01), Dickens
patent: 5806067 (1998-09-01), Connor
patent: 5809500 (1998-09-01), Nolan
patent: 5812849 (1998-09-01), Nykiel et al.
patent: 5813012 (1998-09-01), Chase et al.
patent: 5828890 (1998-10-01), Rehbock et al.
patent: 5878422 (1999-03-01), Roth et al.
patent: 5903895 (1999-05-01), Hoffman et al.
patent: 5926814 (1999-07-01), Fridman
patent: 5930506 (1999-07-01), Bieler
Cummins Engine Company, Inc.
Homere Jean R.
Woodard Emhardt Naughton Moriarty & McNett
LandOfFree
Method for processing computerized date data which spans... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for processing computerized date data which spans..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for processing computerized date data which spans... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2437482