Convert a field to_number and use formatmask

Question

I like to convert a field into a number SRW.Set_field(0, to_number(:fieldname));
as well create this mask 'N.NNN.NNN.NNN.NNN.NNN'
SRW.SET_FORMAT_MASK('N.NNN.NNN.NNN.NNN.NNN'); or SRW.ATTR.FORMATMASK := 'N.NNN.NNN.NNN.NNN.NNN';
All this srw doesn't work, why?

Answer 1

The field doesn't have a datatype. The field's datatype is picked up from the column that is its source. Therefore, the datatype of a field is fixed at runtime and can't be changed.
The srw.set_field_number() built-in only sets the value of a field, it doesn't change the field's type. If the datatype of the source column for a field was not "number" then the above call would have no effect.
Likewise, the srw.set_format_mask() built-in only effects fields whose datatype is number.
It sounds like what you're doing is trying to display both Character and Number values in a single field. The only way to do this with a single field is to base the field on a character column and do the formatting either in the SQL or PL/SQL that is the source of the column. This will limit you to the format masks available in both SQL or PL/SQL.
Another way of doing it is to create 2 fields. One for the number value and one for the character value. Place the fields on top of each other and use format triggers to display one or the other. You can then use the srw.set_format_mask() against the number field if required.