Hi.
You should try field-symbols or dynamic memory.
Declare a field symbol and a charfieldname type 30 char (length of your table's name and table's field)
Example
DATA: f_myfield(30),
f_increm_col(3) TYPE n,
FIELD-SYMBOLS: <f_value> .
BEGIN OF my_new_table OCCURS 0,
row_num(4) TYPE n,
col_name (10),
find TYPE c,
END OF my_new_table.
CONSTANTS: col_numbers TYPE i VALUE 5. "In your case.... if you need you can count number of "columns dinamically
Inside your loop do the following
LOOP AT mytab.
CLEAR my_new_table.
ADD 1 TO my_new_table-row_num.
CLEAR f_increm_col.
DO 1 TO (col_numbers). "Loop through your columns searching for values...
MOVE sy-index TO f_increm_col.
CONCATENATE 'mytab-col001' f_increm_col INTO f_myfield.
CONCATENATE 'col' f_increm_col INTO my_new_table-col_name.
ASSIGN (f_myfield) TO <f_value>.
IF sy-subrc EQ 0.
"Your COL001 has got a value and so you can create an entry in your new table
my_new_table-find = abap_true.
ELSE.
my_new_table-find = abap_false.
ENDIF.
APPEND my_new_table.
ENDDO.
ENDLOOP.
Hope to help
Bye