Running total vs CE-fuctions

Hi.

How to write such SQL-query using CE-functions?

INV_AGGR = SELECT T1."DOC_NUMBER", T1."/BIC/ZAC_DOCNO", T1."DEB_CRE_DC", SUM(T2."DEB_CRE_DC") AS"RUNNING_TOTAL"

FROM"SAPBH1"."/BIC/AZFI_O0100"AS T1, "SAPBH1"."/BIC/AZFI_O0100"AS T2

WHERE T2.AC_DOC_NO <= T1.AC_DOC_NO 

  AND T1."DOC_NUMBER" = T2."DOC_NUMBER"

GROUPBY T1."DOC_NUMBER", T1."/BIC/ZAC_DOCNO", T1."DEB_CRE_DC"

ORDERBY T1."DOC_NUMBER";