how to select data in multiple datatables after using join,group by and order by in Linq

在linq中使用join group by 和order by实现多表联查

最近突然碰到在Linq中使用group实现多表联查的问题，虽然由于时间关系没有细细研究，现在回过头来，终于把问题解决了

 

代码如下：

var results = from s in student

 

                          where rawData.id== queriedid                         

 

                          join c in course

 

                          on s.id equals c.studentId

 

                          group new { c, s} by new { c.ID } into grouped//, rawData.TestResult, rawData.TestComments, rawData.TestCaseName, smallBVTMetadata.Components, smallBVTMetadata.TestName

 

                          let g=grouped.FirstOrDefault()

 

                          let gg=g.s

 

                          let ggg=g.c

 

                          orderby c.studentId

 

                          select new

 

                          {

                              ggg.courseName,

                              ggg.score,

                              gg.name,

                              gg.sex,

                              gg.age,

                              gg.ID,

                          };

 

 在group之后，我们就无法继续访问到s和c，类似s.age,c.score之类的写法都是错误的，因为无法访问到s和c。

另附sql group 用法 http://www.cnblogs.com/wang-123/archive/2012/01/05/2312676.html