Here is the use of Dual
dual( s , x )
Forced association of an arbitrary string representation s with a given number representation x. In QlikView, when several data items read into one field have different string representations but the same valid number representation, they will all share the first string representation encountered. This function can be used in scripts and chart expressions.
In scripting, the dual function is typically used early in the script, before other data is read into the field concerned, in order to create that first string representation, which will be shown in list boxes etc.
If a dual value is too large to fit in a field object, it will be represented by ## and not truncated with ... like a string.
load dual ( string,numrep ) as DayOfWeek inline
load Date, weekday(Date) as DayOfWeek from afile.csv;
The script example will generate a field DayOfWeek with the weekdays written in clear text. QlikView will for all purposes regard the field as a numeric field.