Data Input Buffers for Maintenance Screens
Usually each screen has three buffers.
The clerk typically makes one of three kinds of changes;
If fields did change and the relation between any of the fields is wrong, the program issues a warning and expects the clerk to make corrections or to bail out. If the buffer passes the comparison, the program locks the data base and re-gets from the data base using the keys of the original record. The critical fields of the original buffer must match the corresponding fields in the re-get buffer. When differences occur, the program issues a warning and re-cycles. When no critical differences exist, the program uses the current buffer to update the data base.
Critical fields come in two types: absolute and relative. The status of the record can be an absolutely critical field. The clerk and the program would not make the changes to an inactive record, except to re-activate the record. So if the record became inactive while the clerk was inputting normal data, the prudent action is to declare that the record changed and re-cycle. Names and addresses might be absolutely critical. If the address changes while the clerk is processing, re-cycling is best. The quantity of inventory on hand might be a relatively critical field. If the quantity on the re-get buffer is big enough to handle the current request, then the program would continue even though the quantity does not match the original quantity.
- The original buffer holds the data as first retrieved from the data base.
- The current buffer starts as a copy of the original, and then the clerk possibly makes changes
- The re-get buffer holds another copy of the data base
The clerk typically makes one of three kinds of changes;
- normal business changes: shipping, or reserving, or planning, or preparing for a comparison
- corrective changes, such as a change of status, or a correction to a description.
- key changes, which are special cases. (see Key Changes)
If fields did change and the relation between any of the fields is wrong, the program issues a warning and expects the clerk to make corrections or to bail out. If the buffer passes the comparison, the program locks the data base and re-gets from the data base using the keys of the original record. The critical fields of the original buffer must match the corresponding fields in the re-get buffer. When differences occur, the program issues a warning and re-cycles. When no critical differences exist, the program uses the current buffer to update the data base.
Critical fields come in two types: absolute and relative. The status of the record can be an absolutely critical field. The clerk and the program would not make the changes to an inactive record, except to re-activate the record. So if the record became inactive while the clerk was inputting normal data, the prudent action is to declare that the record changed and re-cycle. Names and addresses might be absolutely critical. If the address changes while the clerk is processing, re-cycling is best. The quantity of inventory on hand might be a relatively critical field. If the quantity on the re-get buffer is big enough to handle the current request, then the program would continue even though the quantity does not match the original quantity.