AT SELECTION-SCREEN ON field

*This event can be used if the user wants checks or validations to be carried out for a particular field on the selection screen.

REPORT ztest.

PARAMETERS: p_field1 TYPE char10,
                          p_field2 TYPE char10,
                          p_field3 TYPE char10,
                          p_field4 TYPE char10.

AT SELECTION-SCREEN ON p_field1.

IF p_field1 IS INITIAL.
  MESSAGE 'Please enter a value in Field1.' TYPE 'E'.
ENDIF.

OUTPUT:

On pressing “ENTER” button or executing the program (F8):