c# - 实体框架使用 linq 返回连接表

Question

我有一些桌子：

table1:
id1
fk_tb2 // this is the fk to table2

table2:
id2
fk_tb3 //this is the fk to table3

table3:
id3
name3

现在我想返回一个类似的表：id1 fk_tb2 name3

有人知道该怎么做吗？谢谢

问候，

Answer 1

连接表并使用匿名类型返回必填字段：

from t1 in table1
join t2 in table2 on t1.fk_tb2 equals t2.id2
join t3 in table3 on t2.fk_tb3 equals t3.id3
select new { t1.id1, t2.id2, t3.name3 }

Answer 2

如果您的导航映射得很好，您可以执行类似的操作

var m = from tb1 in dbContext.table1
        select new {
                     id1 = tb1.id1,
                     fk_tb2 = tb1.table2.tb2,
                     name3 = tb1.table2.table3.name3
                   };

否则你可以做

var m = from tb1 in dbContext.table1
        join tb2 in dbContext.table2 on tb2.id2 equals tb1.fk_tb2
        join tb3 in dbContext.table3 on tb3.id3 equals tb2.fk_tb3
        select new {
                     id1 = tb1.id1,
                     fk_tb2 = tb2.id2,
                     name3 = tb3.name3
                   };