SQL processing in ABAP

Question

I'm learning ABAP from the book
Introduction to ABAP/4 Programming for SAP
by Gareth M. de Bruyn and Robert W. Lyfareff
and read now that SQL SELECTs run like loops. I worked with SQL before and didn't have that idea in mind, I wonder if this is something peculiar to ABAP or indeed, in common RDBMS, such as Oracle, it always works like that.
The book says that the
     SELECT * FROM tab [WHERE condition].     
     ENDSELECT.
functions like a loop - I always thought that the whole result was buffered at once (or at least the first ***** rows for immediate use). Looping for me is a functionality related to Cursors.
Excerpt from the book:
SELECT is a looping command, as you can see by the presence of the ENDSELECT command. When a SELECT is issued against a table, it returns all rows of data contained in that table, one at a time. So the first row returned is available for processing during the first pass of the loop. The second row is available during the second pass of the loop, and so on, until all rows have been read from the table.
Please leave your comments.
Thanks
Edited by: Avraham Kahana on Jun 29, 2008 10:14 AM

Answer 1

Hi Avraham,
    Select-Endselect just behaves like a looping statement, which fetches the data from database table record by record.
But, from the point of performance, this is not a good way to select data from the database table using Select-Endselect.
Instead of going for Select-Endselect  and writing the data within the loop, we select data from database into an internal table and then write the data.
The code snippet goes as follows and  it is better in performance also:
Select *
  from <dbtab>
  into table itab
where <condition>
Then we go for the display of  the records.
Hope this helps you.
Any queries, get back to me.
Regards,
Chandra Sekhar