How to use a flag

Question

I am using a button that will send information to an ALV when this this button is pressed, the select stament will be true for showing the ALV with the correct  information,if the select stament is not true we have to trigger an error message and when the user give a click the ALV will not be presented the system will not change to another screen ,  this could only happen when the select was completed.
if somebody knows how to do this please send me an example i will apreciate it.
this is the segment of code that i am using.
FORM trae_datos94.
  REFRESH i_report.
  CLEAR i_report.
  SELECT * INTO TABLE i_report
  FROM zhrpyt9045
  WHERE clprest = '94'.
  IF sy-subrc NE 0.
    MESSAGE i000 WITH 'here is the message'.
    bandera = 0.
    the screen will be stopped here but i dont know how  to do it
  ENDIF.
ENDFORM.                    "trae_datos94

Answer 1

To clarify,  if you really want to use an information message, then you will need to handle it a different way.   In this example, I have put your select statement in the PAI of the screen when the user presses a button.
Module User_command_100.
case ok_code.
    when 'SOME_FCODE'.
        clear ok_code.
        CLEAR i_report. REFRESH i_report.
         SELECT * INTO TABLE i_report    
              FROM zhrpyt9045           
                 WHERE clprest = '94'.
         IF sy-subrc = 0.
* Build you ALV
* And call the screen.
*           Perform build_alv.
*           leave to screen  200.
         else.
          <b> MESSAGE i000 WITH 'here is the message'.
           exit.</b>
         ENDIF.
endmodule.
Doing it this way will allow you to have your information message and force the program to stay on the current screen.  Make Sense?
Regards,
Rich Heilman