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A typical QlikView application may have one million records in the data, one hundred rows in a pivot table and a single number, a KPI, in a gauge or text box. Although different in magnitudes, all three numbers may still represent all data. The numbers are just different aggregation levels.
There are many functions in QlikView that can help you write the necessary formulae to calculate aggregated KPI:s. Some will collapse many records into one value, others will not. Today I will write about the different function classes, and how you can combine them.
Aggregation functions are special: You must use one to collapse several records into one number – which means that you need them in pretty much any formula in QlikView: In Chart expressions, in Text boxes, in Labels, etc. If you don’t write an aggregation function in your expression, QlikView will assign one for you: It will use the Only() function.
Scalar functions can be used both inside and outside the aggregation function:
Date( Min( Date )
Money( Sum( If( Group='A', Amount ) ) )
There is one restriction: You can normally not use an aggregation function inside another aggregation function. Hence, you usually need every field reference to be wrapped in exactly one aggregation function.
Most places in QlikView demand that you write your expression so that it returns one single value. This means that you must wrap the Aggr function in an aggregation function to get a meaningful result. The only exception is if you use the Aggr function to define a calculated dimension or field. This means that you have two aggregation steps; one nested in the other:
Avg( Aggr( Sum( Amount ), Month ) )
Charts complicate the matters slightly: A chart is like a For-Next loop where the number of distinct dimension values determines the number of loops. In each loop, the expression must return one value only, and this is the value used for the bar/slice/pivot table row.
However, sometimes you need values from other rows in the chart, and it could even be that you need values from several rows. To solve this, there are two additional classes of functions that should be used together:
Example:
RangeSum( Above( Sum( Amount ), 0, 12 ) )
Bottom line: Know your functions. It will help you write correct expressions.
See also
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