Yes i've do it now it works :) infact i've do it like below i think there no different to directly write this code to the DE ? why this alway caths one's eyes ?

* DE BeforeOpenTables() code
thisform.setDE()

* form SetDe method code
Local dbc_path
Select pathcont.datadir From pathcont Into Cursor CrsPathcont && which my keep path info table
dbc_path=addbs(Alltrim(CrsPathcont.datadir)) + "data1.dbc"
this.SetAll("database",dbc_path,"cursor")