update s set s.FieldLexem = '<lx:Cast type="String" xmlns:lx="lexem">
    <lx:Path OwnerQueryLevel="0">
        <lx:StepString name="DSCHET" />
    </lx:Path>
    <lx:ConstOperand type="String"><![CDATA[yyyy-MM-dd]]></lx:ConstOperand>
</lx:Cast>'
from ies.T_SEARCH_CRITERIA s
where s.xPath = '//ZL_LIST/SCHET/DSCHET'
and s.FieldLexem like '%</lx:Str>%'