listOrders.DataSource = (from sp in dbdata.Specifications
join ord in dbdata.Orders on sp.O_id equals ord.O_id
join prd in dbdata.Products on ord.O_id equals prd.O_ID
whe
此查询工作: select ist_id, ist_opis , CAST(ist_sifra as float) as sifra
from IZOBRAZBENA_STOPNJA
where ist_aktivno<>0
order by sifra
,但如果我想只看到只有当sifra = 5,我得到“无效的列名称sifra“。 “ select ist_id, ist_opis ,