Downloadin data form internal table in differnt worksheet of excel

Refer sample code:

* Multiple excel sheets generation in a workbook

CREATE OBJECT EXCEL 'EXCEL.SHEET'.
GET PROPERTY OF EXCEL 'Application' = APPLICATION.
SET PROPERTY OF APPLICATION 'Visible' = 1.
CALL METHOD OF APPLICATION 'Workbooks' = BOOKS.
CALL METHOD OF BOOKS 'Add' = BOOK.
CALL METHOD OF BOOK 'WORKSHEETS' = SHEET.
CALL METHOD OF SHEET 'ADD'.

* Fill all the sheets with relavant data

PERFORM SHEET1 TABLES ITAB1.
PERFORM SHEET2 TABLES ITAB2.
PERFORM SHEET3 TABLES ITAB3.
PERFORM SHEET4 TABLES ITAB4.

* Quit the excel after use

CALL METHOD OF EXCEL 'QUIT'.
FREE OBJECT: COLUMN,SHEET,BOOK,BOOKS,APPLICATION,EXCEL. "NO FLUSH.
CLEAR V_SHEET.


FORM FILL_CELL USING ROW COL VAL.
CALL METHOD OF SHEET 'cells' = CELL NO FLUSH
EXPORTING #1 = ROW #2 = COL.
SET PROPERTY OF CELL 'value' = VAL.
FREE OBJECT CELL NO FLUSH.
ENDFORM. " FILL_CELL


FORM SHEET1 TABLES ITAB1 STRUCTURE ITAB1.
V_SHEET = Sheet Name.
V_NO = V_NO + 1.
CALL METHOD OF BOOK 'worksheets' = SHEET NO FLUSH EXPORTING #1 = V_NO.
SET PROPERTY OF SHEET 'Name' = V_SHEET NO FLUSH.
PERFORM FILL_SHEET1 TABLES ITAB1 USING V_NO V_SHEET.
CALL METHOD OF SHEET 'Columns' = COLUMN.
FREE OBJECT SHEET.
CALL METHOD OF COLUMN 'Autofit'.
FREE OBJECT COLUMN.
ENDFORM.
Repeat above procedure for all sheets you want to add


FORM FILL_SHEET1
TABLES ITAB1 STRUCTURE ITAB1
USING V_NO V_SHEET.
ROW = 1.
PERFORM FILL_CELL USING ROW 1 'Column1 Name'.
PERFORM FILL_CELL USING ROW 2 'Column2 Name'.
PERFORM FILL_CELL USING ROW 3 'Column3 Name'.
ROW = ROW + 1.
LOOP AT ITAB1.
PERFORM FILL_CELL USING ROW 1 ITAB1-Column1.
PERFORM FILL_CELL USING ROW 2 ITAB1-Column2.
PERFORM FILL_CELL USING ROW 3 ITAB1-Column3.
ROW = ROW + 1.
ENDLOOP.
ENDFORM.

Repeat above procedure for all sheets you want to add

Initializing an Internal Table

In case you have an internal table "itab", and you wish to initialize it (clear it), here are some common statements:

CLEAR itab.
This command clears the header of a table, but keeps its content. The initial memory allocated for the table remains reserved.
(If you don't remember what a header line is, you can find out here or here).

CLEAR itab[].
The content of the table is released, and the header line is not (kind of the opposite of the CLEAR command).

REFRESH itab.
Clears the content of the internal table completely. The initial memory allocated for the table remains reserved . The header content is also cleared.

FREE itab.
Initializes the internal table and releases its entire memory space, including the initial memory requirement. So using free deallocates memory.

For more information visit the SAP Help. Also, the following blog has nice examples of what happens to an internal table and its header by using each of the commands above.