关系型数据之LinQ基本查询

var Query= from a in data.A
where a.admin==传入的用户名&&a.pwd==传入的密码(可以传入一个model实体)
join b in data.B
            on a.bid equals b.id into ab
            from r1 in ab.DefaultIfEmpty()
            join c in data.C
            on r1.cid equals c.id into bc
            from r2 in bc.DefaultIfEmpty()
            join d in data.D
            on r2.did equals d.id into cd
            from r3 in cd.DefaultIfEmpty()

select new
            {

//这里是table A 的id;
                  Id = a.Id,

//这里是table B的Name;
                  Name = r1.Name,
                  Pro = r2.Pro,
                  IpAdd = r3.IpAdd
            };

//转成数组形式;

        var list = Query.ToList();

//list[0].Name即表示整个LinQ查询的结果的第一条数据的table B的Name,以此类推;