Insert Data into Hashed Table

REPORT  ZRRSAMPLE.

TYPES: BEGIN OF t_foo,
        field1 TYPE char2,
        field2 TYPE char2,
        field3 TYPE char2,
        field4 TYPE i,
      END OF t_foo.

DATA: lt_foo TYPE HASHED TABLE OF t_foo WITH UNIQUE KEY field1 field2 field3.

DATA: ls_foo LIKE LINE OF lt_foo.

FIELD-SYMBOLS:  LIKE LINE OF lt_foo.

* Must assign it to use it.
ASSIGN ls_foo TO  .

CLEAR .

-field1 = 'AB'.
-field2 = 'CD'.
-field3 = 'EF'.
-field4 = '2'.

INSERT  INTO TABLE lt_foo.

CLEAR .

-field1 = 'AB'.
-field2 = 'CD'.
-field3 = 'EF'.
-field4 = '2'.

INSERT  INTO TABLE lt_foo.

IF sy-subrc NE 0.

  WRITE:/ ' this is the duplidate key'.

ENDIF.