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<< Click to Display Table of Contents >> Filter expression |
  
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<< Click to Display Table of Contents >> Filter expression |
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The complete filter expression is specified in the Filter expr.: field as seen in the figure below.
Figure 1357: A filter expression consisting of three conditions
The filter expression may consist of filter variables, logical operators, and parenthesis.
The so-called filter variables are for example V1 for condition 1, V2 for condition 2 etc. according to the list right above.
Please note that the letter used is configurable. A typical letter is “V”, meaning “Variable”. If changed to “C” for “Condition”, the conditions would be called C1, C2 etc. Any letter may be used.
There are two logical operators available. They are shown in the table below.
Operator |
Description |
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& |
Logical ”and”. Both conditions must be true if the entire expression is to be true.
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/ |
Logical ”or”. At least one of the conditions must be true if the entire expression is to be true.
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A device list containing all devices manufactured by ABB and Siemens should be created. This implies that devices from other companies than the two mentioned should not be included.
Two conditions are needed. The first one should be true if the manufacturer is ABB. The second one should be true if the manufacturer is Siemens. At least one of these conditions must be true if the device in question should be included (logical “or”).
The result is as follows:
V1 !FABRIKAT = ABB
V2 !FABRIKAT = Siemens
V1/V2
If you would try the filter expression V1&V2 (logical “and”), you would receive an empty report. For logical and, both conditions must be true at the same time. In this case, that is impossible since the manufacturer cannot be both ABB and Siemens at the same time.