If you want to add one or more fields to a temp-table definition that are not derived from a specific other database or temp-table field name, use the ADD-NEW-FIELD() method:
tt-handle:ADD-NEW-FIELD( tt-field-name-exp , data type-exp 
    [, extent-exp
    [, format-exp 
    [, initial-exp 
    [, label-exp 
    [, column-label-exp] ] ] ] ] ).
The first argument is the field name in the temp-table. The second is its data type. These two arguments are required. You can also define other attributes optionally, in this order:
  1. The extent of the field, if it has one
  2. The format of the field
  3. The field’s initial value
  4. The field’s label
  5. The field’s column-label
Note: ADD-NEW-FIELD() does not support all of the field options available in the DEFINE TEMP-TABLE statement.
Because these arguments are position-dependent, you must include values for any intervening arguments you don’t specify. You don’t need to include commas or values for optional arguments following the last one you specify. For example, this statement adds an integer field called Sequence to the temp-table, with a format of "9999" and an initial value of 1000:
DEFINE VARIABLE hTT AS HANDLE NO-UNDO.
CREATE TEMP-TABLE hTT.
hTT:CREATE-LIKE("Customer","Name").
hTT:ADD-FIELDS-FROM("SalesRep","MonthQuota").
hTT:ADD-LIKE-FIELD("Area", "SalesRep.Region").

hTT:ADD-NEW-FIELD("Sequence", "INTEGER",0,"9999",1000).