If I understand you correctly you need to know if a certain field name is already in your table.
You can use FIELD(“FieldNameHere”) will return an empty string if field is not in the table and if the field in the table it will return the name of the field. Something like this

IF FILED(‘F1’)=’F1’
*--field exist
ELSE
*-- not exist
ENDIF	

>hi all,
>
>if the field found at my table
>i want replace field data with another field
>if field is = space(17)
>append blank
>replace mytable title fields to new records
>
>something like below
>

>use qcombined1 excl
>ALTER table qcombined1 ADD COLUMN mnt c(17)
>
>&&if qcombined1.f1 found()&& f1 isfield name 
>scan
>replace mnt WITH f1
>
>
>IF f1=SPACE(17)
>APPEND fields name as(no,name,f1,f2........at new record
>
>if field.f2 found()
>
>replace mnt WITH f2
>
>IF f2=SPACE(17)
>APPEND fields name as(no,name,f1,f2........at new record
>
>if field.f3 found()
>replace mnt with f3
>.
>.
>.
>.
>.
>if field.f56 found()
>replace mnt with f56
>
>endif
>endif
>endif
>ENDSCAN
>
>

>thanks