SELECT statement query

Hello all,

         I understand this is a very basic question in ABAP. But, I was just having this doubt and would like to get it cleared before I move on with my development.

There is this piece of code:

  SELECT afield                                        
    FROM atable                                       
    INTO anothertable-afield                  
   WHERE afield EQ btable-afield            

     AND cfield EQ constantvalue.                           
  ENDSELECT.

Wanted to clarify whether the "ALL" the values from the btable will be compared with the afield values of atable. Or, do I need to loop this btable to ensure that all the values are compared one by one?