title: Make a SELECT by field is empty?
body: <p>I need to know how to make a comparison in a SELECT for a field that has to be empty.</p>
  <p>I'm trying to select some fields from bkpf, with the field stblg as empty. I've done it in this way:</p>
  <pre><code> SELECT c~kunnr a~belnr d~spart c~bldat c~waers a~hwaer f~mwskz
        INTO CORRESPONDING FIELDS OF TABLE lt_data
          FROM ( ( ( bsis AS f
        INNER JOIN bkpf AS a ON f~belnr = a~belnr )
        INNER JOIN bsad AS c ON c~belnr = a~belnr )
        INNER JOIN vbrk AS d ON d~vbeln = c~belnr )
        WHERE a~gjahr IN gjahr
          AND a~bukrs IN bukrs
          AND c~augdt IN augdt
          AND a~stblg = ' '
          AND f~hkont = '0034930020'.
  </code></pre>
  <p>Is this correct or do I have to use another thing?
  Thank you.</p>