LINQ怎样查询三个表的连接
三个表的连接怎样写呢，
两个的我是这样写的，可以正常运行，

   LinqHISDBDataContext lqDB = new LinqHISDBDataContext(ConfigurationManager.ConnectionStrings["HISLinqDB_ConnectionString"].ConnectionString.ToString());
        var result001 = from bed in lqDB.zy_bed_mi
                        join unit in lqDB.zd_unit_code
                        on bed.dept_sn equals unit.code
                        select new
                        {
                            dept_sn = unit.name,
                            bed_no = bed.bed_no,
                            bed_status = bed.bed_status,
                            patient_id = bed.patient_id,
                            sex = bed.sex,
                            type = bed.type
                        };

        GridView1.DataSource = result001;
        GridView1.DataBind();

但三个的我就不会写了，
非常感谢。
[解决办法]
var q=from a in table1
join b in table2
on a.field1 equals b.field1
join c in table2
on a.field2 equals c.field2
select new{......};
[解决办法]
一样的写法
var result001 = from bed in lqDB.zy_bed_mi
join unit in lqDB.zd_unit_code
on bed.dept_sn equals unit.code
join sc in lqDB.Categories
on unit.code equals sc.code

select new
{
dept_sn = unit.name,
bed_no = bed.bed_no,
bed_status = bed.bed_status,
patient_id = bed.patient_id,
sex = bed.sex,
type = bed.type
};
[解决办法]
不止两个，N个都可以

不止inner join 可以，left/group join也可以：

var result001 = from bed in lqDB.zy_bed_mi
                        join unit in lqDB.zd_unit_code
                        on bed.dept_sn equals unit.code
                        join x in lqDB.Xtable
                        on bed.xid equlas x.id into left
                        from x in left.DefalutIfEmpty()
                        select new
                        {
                            dept_sn = unit.name,
                            bed_no = bed.bed_no,
                            bed_status = bed.bed_status,
                            patient_id = bed.patient_id, 
 
                            sex = bed.sex,
                            type = bed.type
                        };

[解决办法]
这个和数据库的内连接，左连接，右连接相似。就是多表关联。

原理http://blog.csdn.net/killerggf/article/details/6216102
写的很明白了