游标的问题

string a1,a2
int i
i=1
declare cd cursor for
select bianhao,khtype from kh;
open cd;
fetch cd into:a1,:a2;
do while sqlca.sqlcode=0
dw_1.setvalue( "bianhao", i, a1)
dw_1.setvalue("khtype",i,a2)
fetch cd into:a1,:a2;
i=i+!
loop

这样写为什么显示不出来数据呢，哪里出现了错误