c# - Rows are coming undefined when calling function in postgreysql -

i wrote functon when calling function select * fngettalukbydistrict(); iam getting rows field defined undefined.

function

create or replace function sde.fngettalukbydistrict(in districtname text)   returns table(districtname text) $body$ select distinct talukname village districtname=$1 order talukname $body$   language sql volatile   cost 100   rows 1000; alter function sde.fngettalukbydistrict(text)   owner postgres; 

public datatable getalltaluksbydistrict(string districtname) { return helper.executeselectcommand("select * fngettalukbydistrict('" + districtname + "');", commandtype.text); public datatable getalltaluksbydistrict(string districtname) { return agriculturedetailsdal.getalltaluksbydistrict(districtname); }