dbms_lob.substr

SQL

SELECT DBMS_LOB.SUBSTR(CSUSERATTACHEDFILE01.FILECONTENT, 3, 4) AS blobSubstring
  FROM CSUSERATTACHEDFILE CSUSERATTACHEDFILE01
 WHERE (CSUSERATTACHEDFILE01.CSUSERATTACHEDFILENO=10291)

XML query API

<query alias="testLobSubString" projectedClass="com.taleo.akirademo.entity.AttachedFile">
    <projections>
         <projection alias="blobSubstring" projectedValueType="string">
             <lobSubstring>
                 <field path="fileContent"/>
                 <integer>4</integer>
                 <integer>3</integer>
             </lobSubstring>
         </projection>
    </projections>
    <filterings>
        <filtering>
            <equal>
                <field path="no"/>
                <integer>10291</integer>
            </equal>
        </filtering>
    </filterings>
</query>