用odbc来连接数据库如何知道返回的数据集为空
$Connect_id=Odbc_PConNect("chaxun","cims","wwwwww");
$Sql="select cx_canhao.riqi , cx_canhao.item , cx_sc_item.name , cx_sc_item.unit , cx_canhao.rijihua , cx_canhao.rishiji ,cx_canhao.rishiji-cx_canhao.rijihua as cy, cx_canhao.yueshiji FROM cx_canhao , cx_sc_item WHERE ( cx_canhao.item = cx_sc_item.id ) and( ( cx_canhao.riqi ='$Searchdate'))";
$Result_id=ODBC_DO ($Connect_id,$Sql) ;