MVC新入门，使用linq模型直接导入数据表后，外键关系也自动建立起来。我只想返回一两个表的关系，结果追踪发现方法会自动把所有关联表数据全部导入到对象中，如果对应数据多的话，对效能是不是有很大影响？如何解决
比如
- C# code
return db.aspnet_User.SingleOrDefault(d => d.UserName == UserName)
我预期的目的是只返回这个表的数据，结果追踪发现方法会把其他表的关联数据也导进来
之前还傻乎乎的这么写
- C# code
public FullUserModelList FindAllUsers() { var fullUserModel = from aU in db.aspnet_User join aMs in db.aspnet_Membership on aU.UserId equals aMs.UserId join ue in db.M_UserExpand on aU.UserId equals ue.UserID join aUIR in db.aspnet_UsersInRoles on aMs.UserId equals aUIR.UserId join aR in db.aspnet_Roles on aUIR.RoleId equals aR.RoleId orderby aMs.CreateDate select new FullUserModel { aspnet_User = aU, aspnet_Membership = aMs, aspnet_UsersInRoles = aUIR, aspnet_Roles = aR, M_UserExpand = ue }; return new FullUserModelList { FullUserModel = fullUserModel }; }------解决方案--------------------------------------------------------
在Linq中join连接不是左连接
左连接写法：
- C# code
var b = new Modular.SparePartsModular(); var re = b.GetALL();//查询出库存上下限 var dt = ifs.getPorts(out _total, page, rows, no, desc, null).Tables[0];//ERP备件信息 var ps = from d in dt.AsEnumerable() join r in re on d.Field<string>("part_no") equals r.IFSID into joinedEmpDept from dept in joinedEmpDept.DefaultIfEmpty() select new { IFSID = d.Field<string>("part_no"), Description = d.Field<string>("Description"), Num = d.Field<decimal>("count_variance"), Unit = d.Field<string>("unit_meas"), IN_TRANSIT = d.Field<decimal>("IN_TRANSIT"), Price = d.Field<decimal>("price"), MAX = dept != null ? dept.MAX : 0, MIN = dept != null ? dept.MIN : 0, interval = d.Field<decimal>("count_variance") > (dept != null ? dept.MIN : 0) ? 1 : 0//1安全,0不安全 };