Set analysis is one of the more powerful tools you can use in Qlik Sense and QlikView. Its syntax is sometimes perceived as complicated, but once you learn it, you can achieve fantastic things. There is now an additional way of writing the Set expression, that may simplify your code.
Set analysis is a way to define an aggregation scope different from current selection. Think of it as a way to define a conditional aggregation. The condition – or filter – is written inside the aggregation function. For example, the following will sum the amounts pertaining to 2021:
Sum({<Year={2021}>} Amount)
This syntax however has a couple of drawbacks: First, it is not easy to combine a master measure with different set expressions, since the set expression is hard-coded inside the master measure. Secondly, if you have an expression with multiple aggregations, you need to write the same set expression in every aggregation function.
Therefore, we introduce an additional position for set expressions: They can now be written outside the aggregation function and will then affect all subsequent aggregations. This means that the below expression is allowed:
For master measures, this change will allow a very powerful re-usability: You can now add set expressions to tweak existing master measures:
{<Year={2021}>} [Master Measure]
Lexical scoping
The outer set expression will affect the entire expression, unless it is enclosed in round brackets. If so, the brackets define the lexical scope. For example, in the following expression, the set expression will only affect the aggregations inside the brackets - the Avg() call will not be affected.
The set expression must be placed in the beginning of the lexical scope.
Context and inheritance
Aggregation functions that lack set expression, will inherit the context from the outside: In earlier versions the context was always defined by the current selection. Now we have added the possibility of having the context defined by a set expression. So, now “context” means current selectionor an outer set expression.
Inner set expression
If an aggregation function already contains a set expression, this will be merged with the context. The same merging rules as today will apply:
An inner set expression with a set identifier will NOT inherit from the context. It will inherit the selection from the set identifier instead.
An inner set expression that lacks set identifier – it has only a set modifier – will inherit from the context.
How the merge is made depends on the set assignment for the field; whether it is made with an equals sign “=” or with an implicit set operator, e.g. “+=”. The logic is identical to how current selection is merged with a set expression.
Examples:
{<OuterSet>} Sum( {<InnerSet>} Field ) The OuterSet will be inherited into the InnerSet, since the inner set lacks set identifier.
{<OuterSet>} Sum( {$<InnerSet>} Field ) The OuterSet will not be inherited into the InnerSet, since the inner set expression contains a set identifier.
Aggr()
The set expression of the outer aggregation will never be inherited into the inner aggregation. But a set expression outside the outer aggregation will be inherited into both.
Examples:
Sum({<Set1>} Aggr(Count({<Set2>} Field ))) The Set1 will not be inherited into Set2.
{<OuterSet>} Sum({<Set1>} Aggr(Count({<Set2>} Field ))) The OuterSet will be inherited into both Set1 and Set2.
Summary
Nothing changes for existing set expressions – they will continue to work. But with this additional syntax we hope to simplify your work and your expressions and allow you to re-use your master measures more effectively.
This change affects all Qlik Sense editions from the August 2022 release. It will also be included in the next major QlikView release, planned for late spring 2023.
Strange. It still doesn't work as I would expect it to.
The below gives the total for 2022. And it works as it should for 1 etc back to YearsAgo = {7}. But not for 8 on as there are no records for YearsAgo = {8} etc
The below gives the total for all years. Not zero as I would expect
iF however I put YearsAgo = {8} in the SNSalesEquipAllYrs formula it gives a zero value (as it should)
Its not a big issue for me though. As long as I know it does this
@robert99 Aren't you referring to the same "catch" as I described here?
Seems to me that what you're describing falls in "Works as designed" category, but this design kind of makes few things impossible, or at least much more complicated...
Hello @hic ! Is there a plan to include the aggregation scope (TOTAL) in this outer style, so we can apply totals to master measures? Regards, Sergio Otero.
@hic and how about the inverse precedence of set analysis? In other words, outer set analysis overrides inner? That could as well be related to the outer TOTAL.
I agree with your example. Although like you I hoped the outer set when using the same field overrode the inner set but can understand why it was done the way it was. And can easily work with how it works
But I think my example above is a bug. I do not have YearsAgo in the inner set and it works fine until YearsAgo = 8 (an option that should give a zero balance as 8 years back was not in any table). We only loaded data from 7 years back on.
It works with {<[Brand site]=[Comparison]::[Brand site]>} Sum({<Rolling={1}>} [Line total amount after discount incl. tax]/[Exchange rate])
I had a $ in my previous expression {<[Brand site]=[Comparison]::[Brand site]>} Sum({$<Rolling={1}>} [Line total amount after discount incl. tax]/[Exchange rate]) and that's why it doesn't work.
This new feature is very useful and it's an incredible time saver !
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