Date range on USGRP_USER - no selection.

Like USR02, USGRP_USER has a validity range. When selecting from USR02, you have to treat an empty validity date field as beginning (or end) of time.

    SELECT usgrp_user~bname usgrp_user~from_dat usgrp_user~to_dat
           usr02~gltgv usr02~gltgb
        INTO TABLE userids
        FROM usgrp_user
        INNER JOIN usr02
                ON usr02~bname EQ usgrp_user~bname
        WHERE usergroup EQ c_deputy_user_group
*          AND ( from_dat LE sy-datum OR from_dat EQ '00000000' )
*          AND ( to_dat   GE sy-datum OR to_dat   EQ '00000000' )
          AND ( gltgv    LE sy-datum OR gltgv    EQ '00000000' )
          AND ( gltgb    GE sy-datum OR gltgb    EQ '00000000' ).<br>

I've a bunch of valid users, with valid groups - some with the dates set, some not. At the moment, I'm looping through userids, after the select.

    LOOP AT userids ASSIGNING <userid>.
      CHECK ( <userid>-from_date LE sy-datum OR <userid>-from_date IS INITIAL ) AND
            ( <userid>-to_date   GE sy-datum OR <userid>-to_date   IS INITIAL ).

Now, if I uncomment lines 2 and 3 of the WHERE clause, I'd expect not to need that CHECK. But then the SELECT gets no data...

Any ideas?