Getting The Records That Not Linked With Any Related Records

<fetch version="1.0" output-format="xml-platform" mapping="logical" distinct="false" ><entity name="quote" ><attribute name="msdyn_account" /><attribute name="name" /><attribute name="quotenumber" /><attribute name="msdyn_ordertype" /><attribute name="ets_quotationtype" /><filter type="and" ><condition attribute="ets_quotationtype" operator="eq" value="964720002" /><condition attribute="statuscode" operator="eq" value="4" /></filter><link-entity name="ets_onetimevisit" from="ets_quote" to="quoteid" alias="One_Time" link-type="outer" ><filter type="and" ><condition attribute="createdby" operator="null" /></filter></link-entity></entity></fetch>