Databases Reference
In-Depth Information
Another thing you may notice in the final result is that some values have a hyphen
symbol (
-
) instead of a value. This happens when the result of the expression is null
or missing. We can illustrate this by creating a temporary table box containing the
Airline
,
# Departures Performed
, and
# Departures Scheduled
fields. We will see
that, while
40-Mile Air
has actually performed flights, none of them were scheduled.
This means that the
Performed vs Scheduled flights
KPI cannot be calculated
(division by zero is not possible).
Note that, in a table box, each possible combination of values resulting from the
enabled fields will occupy one row. All table records in the data model resulting in
the same combination of values are grouped into a single row. In our example,
40
Mile Air
could have 10 records with
1.00 Departures Performed
and these will all be
grouped into a single row in the table box.
If we want an exact count of the number of rows for each combination of dimensions,
we need to use a straight table and include the count function as an expression.
Not all expressions are numbers
A nice feature of straight tables (and pivot tables as well) is that not all expressions
need to be numbers. Take a look at the
Expressions
tab of the
Chart Properties
window and you'll see a drop-down menu labeled
Representation
. By default this is
set to
Text
, but there are other interesting options:
• Image: This option works in the same way as the text object we used earlier.
For example, we could use this setting to display an upward arrow when a
certain indicator is showing positive results, or a downward arrow in case of
negative performance.
