Table control are treated like a loops in BDC.
actually the transfer the data from the program to screen is
automatic. but where as in table control is not automatic we
should pass the data to the table control we should pass the
data thorugh the loop statement .

This is defined in Both the PBO Event.Because of the table
control is where you should be transferred the data with the
loop only. 

table control syntax is like this:

control (tc) type table view using screen (sno)

important parmaters:

1. Lines: No of displyable rows in a table.
2. Top-lines: The row of the table where the screen should
be start.
3.scroll: currently being using inside the loop statement.

if u update the value in table control that value is updated
with the same value. this is possible with the table control
only.

Table control in BDC is maintained by knowing the number of
 records in the table control and then calculate visible
rows in the table. Visible rows in the TableControl are
calculated using the data structure CTU_PARAMS. It consists
of the default values (field). 

Ex: defaultvalue = p

      then P+,P++ to move the records up and
           P-,P-- to move the records down