Database Management
Reference Manual
Introduction to Database Concepts
:
Database Sessions
: Set a Comparison Date
Set a Comparison Date
Within AVEVA E3D™ a comparison date can be set. A convenient way of doing this is to use a stamp. However the comparison date may also be set to an explicit session on a particular extract. If the comparison session is on a different extract then the extract must be an ascendant of the current extract.
Any query may then be done at the old session using the 'OLD' keyword. e.g.
Q OLD XLEN
This would return the value of XLEN at the comparison session.
Pseudo Attributes for Comparisons
There are a number of pseudo attributes that can be used to do comparisons. These are listed in the database reference manual.
1974 to current year.
AVEVA Solutions Limited and its subsidiaries. All rights reserved.
