有三个表:
Product(uid,typeid,cname) ,Product_subtype(uid,typeid,cname) ,Product_type(uid,cname)Product.typeID =Product_subtype.uidproduct_subtype.typeId=Product_type.uid现在想查询product_type.cname="AAA";的product,并绑定到combobox.NorthwindEntities context = new NorthwindEntities();context.product.where ////应如何写combobox.datasource= //应如何写
Product(uid,typeid,cname) ,Product_subtype(uid,typeid,cname) ,Product_type(uid,cname)Product.typeID =Product_subtype.uidproduct_subtype.typeId=Product_type.uid现在想查询product_type.cname="AAA";的product,并绑定到combobox.NorthwindEntities context = new NorthwindEntities();context.product.where ////应如何写combobox.datasource= //应如何写
然后在combobox里面绑定相应的属性,比如显示属性为cname,value值属性为uid。
估计楼主还是要把3个表链起来,但这3个表具体是什么关系?主从关系吗?
给个例子你tb1和tb2是主从关系(主键danhao)
, tb3和tb4也是主从关系,代码是把结果合并和建立新的WW并赋值
var query = (from a in myff.tb1
join b in myff.tb2
on a.danhao equals b.danhao
where //条件例如a.riqi >= dateTimePicker1.Value
select new { a.riqi, a.duifang, b.guige, ww = "入" })
.Concat
( from c in myff.tb3
join d in myff.tb4
on c.danhao equals d.danhao
where 条件
select new { c.riqi, c.duifang, d.guige, ww = "出" });
NorthwindEntities context = new NorthwindEntities();
var query=from p in context.Product
let type=from sub in context.Product_subtype
join t in context.Product_type
on sub.typeid equals t.uid
where t.cname=="AAA"
select sub.uid
where type.Contains(p.typeid)
select new{p.cname,p.uid};