You know, I never really, really thought too much about it before for some reason, but Henric Cronström’s post on data types makes sense: Qlikview doesn’t have them.
There are no data types in QlikView.
This is not a limitation – it is conscious design decision.
One of the initial requirements of QlikView was that it should be possible to mix data from different sources: We wanted users to be able to have a data model with some data from a database, some from an excel sheet, and some from a comma delimited text file. Some of these sources have proper data types, others don’t. So relying on the data types of the data source would be difficult. Further, we wanted the internal functions to be able to always return a relevant calculation – there must never be any type of conversion problems. We wanted simplicity for the user.
Enter the Dual format.
The dual format is a brilliantly simple solution to the above requirements: Its core is that every field value has two values – one string that is displayed, and one number that is used for sorting and calculations. The two values are inseparable; they are like the two sides of a single coin. They are both needed to describe the field value properly.